Under BES 4.1.x you would need a third-party product to do this, AFAIK.
There is kinda a fudge way (at least on Domino) to push the corp address book to devices, but it pushes it in place of the user's personal address book, and I don't know whether your users would like that. Mine certainly don't. So they are stuck with a local PAB on BB, and having to lookup for corp data.
: Groupware Infrastructure Architect, Denver CO If I'm not here, I'm playing World's End on FaceBook. Mob/Mafia Wars are SOO last year