There is a new model that might be out on January 08.
"This could launch as soon as January and as late as April, although we’ve heard whispers it might even be officially announced by RIM today during their quarterly earnings report."
http://www.boygeniusreport.com/2007/12/20/blackberry-9000-myth-or-reality/
New Blackberry 9000 (not series) which might have a Full touch screen 3G, Wi-Fi. And will be for GSM networks.
But if you cant wait you could go for the Curve but i would go for the 8320 because of the Wi-Fi and use the Google Maps as a GPS device.