http://www.tuaw.com/2008/08/14/simplify-media-for-iphone/Download this while it's free!
First 100,000 downloads will be free then $4 after. It's partly a wifi/cellular based iTunes remote I think, but primarily will allow you to stream your iTunes music over wifi/cellular networks...essentially allowing you to have you entire music collection wherever. Haven't had a chance to test it yet what with being at work and not having access to my home machine, but with 3G speeds it could be quite good.
Enjoy
(And you may as well download it now and delete it even if you don't want to use it...afaik even if they put the price up you can download it again for free once it's been purchased)
