I thought I'd give a definitive answer to those of you who ask about BBerry in Japan. I could not find a BBerry that worked in Japan before I left for Japan, although that may have changed with the 8830.
I bought a Nokia E61i with BBerry connect before I left. I am on the AT&T (Cingular) network. AT&T said that there was little or no chance that the Nokia E61i would work in Japan -- 7 different "international specialists" agreed on that.
I am here (in Tokyo) to tell you that the E61i w/BBerry connect works perfectly. From the time the plane landed at NRT, I have had perfect BIS BBerry reception.
Make sure that AT&T has your correct IMEI for the Nokia phone. They will tell you that they cannot give you 3G service, but that is because the E61i has 2100 Mhz. 3G -- exactly the one that Japan requires (but the 3G wont work in the US/Canada). Also, make sure you have "International roaming" enabled.
I have seen 8700 devices here,that work, but I have no idea how that can be. The Nokia isn't as user friendly as the real BBerries, but, it works fine.
Regardless of what you hear from AT&T...

UPDATE: In Japan, I found 2 providers: SoftBank and NTT Docomo. Softbank apparently has an agreement with AT&T, so this network worked fine. I could get NTT Docomo service, but no Blackberry Connect. So, choose Softbank.