Will the iPhone 3G become flash compatible, or is that something you would have to buy from the application store?
I'll sum up every answer you're likely to get, in order of most likely to least likely.
1) No, flash will never work on the iPhone.
2) Yes, but you'll have to buy an application from Adobe and it won't work in Safari, but outside it. Web links will send you there.
3) You won't need it because web developers won't want to lose iPhone viewers and will start doing everything in Java or SproutCore.
4) Not really, but some 3rd party company will offer a hack that will make Flash work. Sort of.
5) Yes, Adobe will make a deal with Apple to put it in Safari
6) Yes, Apple will fully support Flash on their own soon.
There you go. Take your pick!