T-Mobile has roaming agreements in Russia -
http://www.t-mobile.com/internationa...geInternet.asp - note that voice is $4.99/minute (yikes). So a 7290 on their network would work.
Cingular has roaming also (voice is only $3.99/minute) -
http://www.cingular.com/customer_service/roaming_gen - but I can never find their GPRS roaming agreements.
Best bet is to call these two and double check. Verizon, Sprint and Nextel will not work there at all. Good luck!