Will you be abroad long enough to want to have complete BB service from a foreign carrier? If not, do as NJBB says and pay Cingular the extra $20/mo for unlimited global data, then get a local phone+SIM for voice. If you'll be going to several places, your options are to either pay Cingular's high international voice roaming charges, get a SIM for everyplace you go, or get a SIM that has lower-cost international roaming. A cheap unlocked phone from ebay is all you'd need for voice coverage.

Out-of-North America BB services could force you to get a new hosted BES/MDS provider + deal with customer service that could be even worse than
Cingular's. I thought about this for an upcoming 4wk trip, and it was a very poor option for me. If I were going to be gone for a year, I might have to think again. You might want to get a different BB, since things like EDGE + US based OS might not do what you expect with an overseas provider.