No, there is no GPRS data roaming partner in Argentina for T-Mobile...
See:
http://www.t-mobile.com/internationa...geInternet.asp
In Central and S. America, T-Mobile has roaming agreements in Mexico, Brazil, Venezuela, Chile...
BTW: Having International roaming is QUITE different than having a GPRS roaming agreement for the country. The Blackberry will work fine as a telephone but NOT as a data device while roaming in Argentina. Here are the two roaming partners:
http://www.t-mobile.com/internationa...R&CN=ARGENTINA
Editing to add that ATTWS doesn't have any agreements for Argentina and GPRS data:
http://www.attwireless.com/internati...2&DID=86&CDID=