GPS.

By the time WIFI is really widely used, you will have upgraded your blackberry anyway, every time i'm in a wifi area is at work, at home, or a starbucks or the like. Starbucks charges you, so I may aswell use the included data on my plan, and at home and work, I would rather browse on my PC!

I had a windows mobile device with wifi on, and never really used the wifi, The GPS on my 8310 however, is incredibly useful, just for the fact it has walking directions included, not just driving. If I go to a city I don't know I can find my way round successfully now!

And the silver is nicer on the 8310.