Wow! At least one (probably the only one, hehe) of Rand's predictions is already coming true. There has been, for a while now (more than a year from what I heard), a CMS that allows you to build Digg-like platforms: PLIGG. And let me tell you, there is a bizarre TREND in most of the names - most of them are utterly funny with their "iggish" or "tube" style:

Riggd  Digg-like news with a patriotic community (who launched that!!)
Dealigg  Digg-like e-commerce site with "deals." It even has a Black Friday section!
GameDiggity  Digg-like YouTube videos of gamers / games
ScoopTube  Digg-like best viral videos. The design is not top tier, though.^
Jossle  Digg-like political news
GameSnips  Digg-like gamers information (walkthroughs, etc.)
TheBigMashup  Guess it: Digg-like mashups
TalkSoccer  Digg-like soccer fans site

Unless I'm wrong, the guys behind this are the guys who launched VideoSift, which is a digg-like platform for YouTube videos.

All those sites still have a low traffic count, but I believe some could do well in niche markets if they are well targeted (not necessarily the ones above, although the most successful ones so far seems to be doing fine).

My only concern about this is the long term reliability of such a solution--updates, dealing with mass traffic, languages, etc.

What are your thoughts?

*UPDATE: Get your Niche market social bookmarking site with IwillSearchU post about Direct Links from small bookmarking vertical sites. Thanks tpiddy (by the way, it would be great if you would have a about you page on your site, we can even guess your name with your nickname!).

**UPDATE #2: Ryan Knowles mentionned me that there is a Pligg site which talks about Internet Marketing / AdSense / SEO, so for people like me and you looking to boost their SERPs, I'd recommend you try PlugIM, which was already reviewed by Wired, Seth Godin and Steve Rubel. Thanks Ryan!