From Daring Fireball:
The single most popular thing people use Flash for is to watch YouTube videos, which you can already watch a subset of using the native Mobile OS X YouTube app. In short, is the lack of Flash keeping people from buying iPhones and iPod Touches?
I say it's holding back some.
For one, my eBay auction advertisements (called "eBay To Go") don't show up without flash.
Two, Without Flash there's no Senor Cardgage