http://www.dottunes.net/products.html
Well I downloaded the software and paid a tenner to have the iPhone functionality applied to the software.
I'm very impressed. I can now stream all my music over to my iPhone in crystal clear sound - in fact I would go so far as to say the music sounds better streamed than being installed on the iPod part of my iPhone - the iPod equaliser doesn't come into play.
It's basically quicktime that is playing back the music - but it sounds great. I can now go up to bed and listen to ALL of my music, including podcasts etc without having to install them onto my memory.
My iPhone just became a 60GB iPod (or whatever size your iTunes library is) whenever I am in a wi-fi area!