Wow, it sounds just like intrusive flash ads! What a surprise! I guess when Apple's doing it, it's a good idea, huh?
You have to click on the ad to get the experience. You don't want the experience? don't click on the ad. I wouldn't call that 'intrusive'
When and if they build ads that take over your screen real estate, forcing you to close them THEN I'll join in the chorus of anger, but for now I don't see the problem at all. With luck this will trigger some neat creativity...
As an aside I think this can only help the adoption of html5 on the net. I agree with the macbidoulle poster, agencies that develop iPhone iAds are unlikely to rebuild them in flash for the web, they'll steadily gravitate to standardising on html5... nice one....