MSN Money has a fascinating report on the reaction to Apple's unveiling of the iPhone at January's Macworld. If any event could be said to trigger a groundswell of grassroots reporting, it was the iPhone. In fact, the iPhone certainly set new records in that regard with a huge response of rich media--podcasts, photos, videos, hands-on reports and more.
According to the MSN article, the iPhone was mentioned by more blogs for the next 10 days than either McDonald's or George W. Bush. Wikipedia had an iPhone entry within minutes of Jobs' keynote speech. Nifty article, well worth a read.