Everyone knows the story: Sir Tim Berners-Lee at CERN writes some newfangled "hypertext" thing, hooks it into some unknown "Internet" thing, and the WWW is born. Millions of people join services like AOL and Compuserve, the majority to look at a few very static web pages and find porn on the much-older and more established (read: more porn) USENET forums.
We might call this time "web 0.0", if we were into such things, but we're really not. In any event, it was certainly the dark ages of the web: finding content even remotely related to your topic of interest (sans porn, of course) was immensely difficult, and once found, you'd usually end up sated if only because the painful task was complete and cease the search right there.
The next age would bring light into the world of the web, but it would be the neon light of commercialism.
This age was, of course, the famed Dot-com boom. Recollection here should be immediate, so I won't bore with details. Suffice it to say the free market finally realized what these "Internets" might be good for, and capitalized with reckless abandon. This is also about the time that the age of web crawlers was dawning: useful tools no doubt, but much more so when the haystack is as small as it was then.
So while these new tools might help you find a bit of meagerly useful content (mostly static, unattributed, and never primary source), in reality they just made it easy to find the best place to buy books or pet supplies, sell your car, your body, or even your soul. You can pour money into the monster indefinitely, but it'll always want more.
By the time the boom busted, the haystack had grown a lot larger. We're talking big. And it just kept growing, but it wasn't getting much easier to find anything unique, interesting; new. A couple of hippies named Sergey and Larry thought they had found a better way of searching the haystack, and they had... kind of. Searching more of the haystack faster and with more forethought is great, but we're still talking evolution - not revolution - here kids.
The problem wasn't that people weren't publishing to this medium. Without a way to publish and a way to propagate, content languished in obscurity and its authors quickly lost interest in producing more. It was that the signal - the unique content - was getting utterly drowned out by the noise: what are search engines but impressive noise filters anyway?
My point of this whole diatribe is this: its not a coincidence that the "social" web (the true meat-n-potatoes of this new age) and the "blogosphere" have grown up in lock-step.
Case in point: del.icio.us. On the surface a minimalistic tool for storing links and categorizing them. Used to it's fullest it's an amazing way to find content that is much more likely to be of interest to you, if only because you've gone from relying on an algorithm's choice and are now relying on another human for guidance. Without any extra effort of course, because we're nothing if not lazy.
It helps me to think of it like so: "web 2.0" and the social connectivity it has endowed have allowed all the single "point sources" of information (content producers) in the "universe" of the web to begin to organize themselves into more closely-connected groups. Only here can the self-publishing of primary source content thrive.
Each new piece of content is a signal, being sent out by its publishing site: it has some "strength" and therefore can only travel a certain "distance". In the early web, the content producers were so "far apart" that the signal was never picked up, so it dissipated. Now, the simple fact that content producers have begun to move "closer together" allows even low-energy signals to be picked up by another and possibly "retransmitted" (attributed, linked-to, etc), amplifying its impact in the space.
The "social" web has moved these sources closer. It has brought sources that were producing similar content to the point where nearly every signal is picked up by at least one other interested party, because the "distances" involved are so much smaller. This is why Gruber will consistently get picked up by TUAW and the like, but wouldn't ever be seen on Kos. Gruber and TUAW are seperated by a short distance; Kos is quite distant from both, but not at all far from a source such as The Hotline.
Now I realize this must be approaching a thousand words or so, and the writers at Valleywag would have my nuts for this, so it's time to Wrap. It. Up.
What is "web 2.0"? The technology hasn't really changed (bring up AJAX, get my fist in your face), so what did? People, and the way they use it, of course: we stopped searching the haystack one-by-one and started helping each other. Marx would be proud; the social revolution has begun!
 My choice back in the day was none other than the O.G. Gansta' itself, WebCrawler.
 For the record, a term far worse than "web 2.0".
 Yahoo! tried this for a long time, but through a single point of contact, and it's no wonder it failed. And no wonder they were the ones who bought Del.icio.us.
 When I speak of distance here, I mean in an abstract space of semantic distance where the further away two points are the harder it is for one to "hear of" and become interested in another.