I have it on good authority that wireless music sync is definitely not in the cards. A shame that with such a "connected" wireless device, you have to attach a 1990's USB cable to it to get any of your own information/content onto it.
I can't fathom the thought process at the Apple design meetings about this. You can wirelessly purchase music, but you can't wirelessly transfer music to the iPhone that you've previously purchased with iTunes on your computer. What a backwards little device in so many respects.
Wifi kills the iPhone battery real quick. So by going cableless for music syncs, you get all your new music right about the time you need to dig out the cable to charge anyhow.
I do wish I could sync other stuff wirelessly though. Mobile Me should do that well enough when it comes out, though I do wish I could get the same capabilities on my own servers.
So no background applications...
What if I wanted to write a small app that sat in the background and posted my latitude and longitude to my website every 5 minutes, but would still allow me to surf the web and make calls.
There will be support for
background notifications in September. It doesn't sound like your idea would work under this setup though.