I'm not sure that each of these deserve their own separate blog post, but they've been rolling around in my head long enough that at least some attention is probably warranted:

1. Is NoFollow Really NoFollow?
   Danny Sullivan brought up at his SMX Madrid keynote that he felt the engines were probably already "special casing" certain websites and pages that use nofollow on outbound links and "following" them for both discovery and potentially to provide ranking weight. Certainly, they'd have to lie about this in public or risk massive manipulation, but I have to admit, the quality of links on Wikipedia has dramatically improved since they instituted nofollow, and if I were running an engine, those would be links I'd probably want to at least test and probably count.
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2. Domain-Level PageRank
   There's been some speculation that PageRank isn't just used on the page level (#2 on Matt's list). Internally at SEOmoz, we've often discussed that it's very likely the engines run a domain level link metric on the domain graph itself - a pretty easy process when you think about it. Just take all the links on all the pages on a domain and imagine condensing them down to one page, then run a "PageRank"-like algorithm on domains, rather than individual pages. I'm guessing this produces some very useful and usable data for search rankings.
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3. Are SEO Flags a Bad Thing?
   A question that keeps popping up stems from the feeling that Google and the other engines want to find websites where "SEO" is being performed and penalize them or perhaps run them through stronger spam filters simply because they use things like nofollow on internal links, noarchive meta tags, very targeted internal anchor text, etc. I'm not sure that I've come to a full conclusion on this subject, but I tend to lean to the side that thinks it's BS. I'd estimate from experience that 40%+ of Fortune 1000 websites and 60%+ of the top 10,000 most important domains on the web do SEO of some kind. There might be flagging systems for aggressive over-optimization, just as there have always been, but penalties just for doing SEO seem fairly outlandish to me.
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4. When Will Knols Rule the Index?
   I can't imagine Google not wanting some of that amazing, high quality search traffic to stay on Google properties (other than YouTube, of course), so when are Knols going to become the new Wikipedia? I can't imagine it's more than a few years before we see every broad query under the sun featuring highly ranked Knol pages - it's just too irresistible as a Google shareholder to explore that potential revenue channel.
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5. Internationalizing on Domains Back in Vogue
   With the launch of Webmaster Tools' geo-targeting option, I thought we might well see a move to keeping multi-lingual and international-targeted content on a single domain (seomoz.org/de/ and seomoz.org/fr/ instead of seomoz.de and seomoz.fr), but hearing the chatter from international SEOs, it doesn't work nearly as well as you'd think to geo-target subfolders (maybe that's an error Google's working on) and people in other countries (particularly France, apparently) don't like to click on ".com" or ".org" TLDs - they prefer ".fr." This extends to branding and conversion rates, too - web users in France like to buy from websites in France that end in ".fr" and the test data, according to the venerable Andy Atkins-Kruger, is there (though not available in a publicly accessible document, sadly).
   
   If CTR and branding are concerns (and they generally are), maybe we need a new way to tell the engines "Hey, all these domains are run by this singular entity and if you trust one of these sites and think it's important, you should pass along those metrics to these others domains." Personally, I think they already do this to some degree, which is why you don't see usually new domains registered and launched by large, important, trustworthy organizations suffer from the same effects as new sites launched by small-time webmasters.
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6. Yes, Matt Cutts Said All Links to a Domain Help Every Page on That Domain Rank Better
   Danny was complaining that Matt dodged the direct question three times in rapid succession at SMX Advanced, but that's an answer in and of itself. If the answer was "not always" or "no, not really," he'd be pretty happy to share that. Reading between the lines with what Matt (or other search engineers) say isn't a fine art in this case - it's stunningly obvious. The answer is "yes" - every (good) link to a domain helps all the content on that domain perform a little better.
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7. Is There Still a Debate on Nofollow?
   If there is, I can't see why. Go try setting up a nonsense domain, pointing some links no one will find at it, and test for yourself. If you have three links on a page and nofollow one of them, more ranking power and link juice will flow through the remaining two. Now, maybe you think that's only having a small impact, but if you're into "optimization," then you really shouldn't be ignoring any method that's going to help you rank better. Smart black hats did this years and years ago by pointing to the pages they didn't want to pass link juice to with external javascript re-directs or links embedded in Flash. Why would the tactic suddenly stop working now that we can use the more convenient "nofollow" tag?
   
   If you think it's low on the totem pole of "to-do" items, that's one thing, and in many cases I'd probably agree. But to say that no one should ever do it because it doesn't work, or because they're too dumb to figure out how to do it properly, sounds like you're either in denial or don't want competition. I'm also at odds with the argument that we shouldn't be doing things just for the engines - we do robots.txt and meta tags and sitemaps and verification with webmaster tools and yes, even title tags (seriously, no one sees those things up in the corner of their browsers) JUST FOR THE ENGINES (and maybe a teensy, tiny bit for accessibility reasons, but take away engines and I think 90% of that stuff is gone). We have to do lots of stuff to make sites and pages accessible to search engines - that's why our jobs are important.

Obviously, as always, I'm sharing my personal opinions, colored by my experiences. I'd certainly love to hear community feedback.

p.s. One more thing - my amazing fiancèe, Mystery Guest, wrote a blog post for SEOmoz, her first one in many months, on the subject of sexism in social networks & on the web as a whole. We were a bit concerned that it might have a negative backlash (as it's not light material), but figured we'd ask for the community's opinion first.

p.p.s. I cleaned up almost a half dozen inaccuracies or unclear language in this post. Thanks to everyone who emailed me about these!