Noviota: What I'd like to know is if you get a publicly routable IP address, rather than the silly 10.x.x.x I get using GPRS on my current phone.
Also how well vodems work with linux.
I have not setup a Vodem in Linux myself, but the support is built into the kernel of any modern distrobution, no driver download neccesary.
It works as a generic USB serial device. ie /dev/ttyUSB0 and from there you use it like a dialup modem, except dialing with ATD*99#, i think.
http://ubuntuforums.org/showthread.php?p=1774427
You don't get a RFC1918 address unless you're using the www APN, change APN to 'Internet' for a publically routable IP address.