i have tried the link on official blackberry site, but it failed to download, i am in china, i bought an unlocked one, so i am not a signed user, did you guys have a link to download, or send me a copy of the official Google talk, (or the serial number for IM+ is also ok). many thanks

Download App World.

They are all listed in there, you download it from mobile.blackberry.com

Another alternative is downloading it from the Google Mobile app page: Google Talk on your mobile phone