And yet this isn't the huge news about iAds. Here is what makes it a big deal: Apple built the network and is offering it up to developers to use how they'd like, with 60% of the revenue made on those ads going to developers themselves. That's up a bit from the standard "Apple gets a 30% cut" rule of thumb, but more than half seems more than fair. Apple hosts and sells the ads, and developers take home over half the revenue.
The ad demonstrated live actually looked cool: they showed off little Toy Story 3 ad at the bottom of a news app. Tap the ad, and it comes up with some options (a character list, sounds from each character, etc) and even a game to play, including an option to buy a game from right within the ad. Steve even asked if anyone had seen anything like this before, and among the gathered press, he got silence in response.
Currently, the most educated of guesses is that the AdKit API will be a developer source as well as an iTunes source (iTunes sources are where the App Store and Music Store get their content.)
After the event in the Q&A session, Steve said they attempted to buy AdMob and got sniped by Google, so they bought Quattro and are trying very hard to come up to speed on what web advertising is like, presumably so they can change it. As long as they aren't trying to get me to refinance my mortgage or whiten my teeth, I'm looking forward to the future of advertising on the iPhone.