I can't find the link right now, but there is an adapter out there that lets you use your decent headphones with the iPhone. I think its a belkin or something. Just looks like a 1-1.5" long flexible jack extension that has a very small diameter around the plug so it will fit in the hole. Its a real shame that you are forced to use an adpater like this to use real headphones, but i'd be ordering this adapter instantly if I decided to get the iPhone.
The stock apple headphones are fine, assuming the ones that came with it are similar to the ones that came with my nano, but my $15 Koss KSC75 are probably twice as good, and i'm sure a lot of people buy better headphones than I do. Its not like you are going to be using nice wireless bluetooth headphones, since it doesn't support the A2DP profile.
Enjoy the iPhone. Despite all the shortcomings, its a really nice looking device that does a lot of things phones should have been doing for years.
** Found the link, http://www.ilounge.com/index.php/ipo...er-for-iphone/ **