I've thought for a long time that "Web 3.0" will probably be based on some form of curated user-generated content for immediate satisfaction, combined with deeper original content produced by specialists.

One big problem we have today is that many on-line social sites become closed and introverted, which leads to the Internet echo chamber phenomenon. Heck, you're reading one of the best examples right now. Such places can still be interesting, informative, and insightful (as posters on another good example might put it) but they also tend not to introduce dramatically different ideas very often, which means that while you can learn a lot in the first few months of following the discussions and perhaps the early days of contributing, the useful-signal/noise ratio drops rapidly once you've seen 90% of the groupthink before.

Another big problem is that it's not just the sharing of citations (in whatever form) that is becoming a flood, it's also the content itself. The Internet is full of blogs where most of the ideas are not really new and original, most of the analysis is fairly superficial or based on second-hand thinking, but every now and then the author writes a gem and attracts attention. Perhaps this is human nature, but I think it's often a case of a blogger who has potentially interesting thoughts to share but who simply lacks the time or inclination to do detailed research and editing of their posts, making the hit-or-miss-but-mostly-miss result almost inevitable. Thus not only the aggregators/social news sites but also many of the sites they link to become a flood of same-old-story material.

I think people are going to tire of this before very long, as we start to realise quite how much time we waste maintaining superficial on-line relationships and consuming superficial content. However, it is difficult for anyone with life's many other commitments to do a good job of producing good content or of filtering what's out there. Sooner or later, we're going to have to admit that there is value in good content (including proper research, careful presentation, etc.) and either people who want to produce it as a hobby will have to spend more time writing fewer (but better) things or people who want to consume more good content are going to have to pay smart people to create it as a real job. Likewise, there is value in good curation, but having someone who can pick out a manageable level of good content to present to a community without becoming repetitve and while actively seeking relevant new ideas from new sources is often not a job you can do in an hour a night, either through your own work or through focussing a user-generated stream that accepts submissions in real time.

I'm not sure we're ever going to get an idealised situation because every individual has different interests and, just as importantly, might be interested in different new ideas if they found out about them. But I'm pretty sure we can make a decent first approximation, at least as good as any of the big name on-line social discussion sites today. We're just going to have to pay for it, one way or another, sufficient to attract the relatively few people who are both willing and able to produce and curate really good content if they have the chance.