I do it almost daily from my iPhone.
http://www.jaaduvnc.com
Edit: Whoops. Sorry, I should have read your entire post first. You won't be able to use an iPhone app to xfer files...
Anyway, Macs have built-in remote screen-sharing. All you need is a VNC client and you're good to go.
Edit again: On a side note, and to expand on what silentsim said, MobileMe really is a decent investment. For everything you get, $99 a year is chump change.