Hello there,
Welcome to the forums, Im new to the forums aswell.
From what I know the are no games avalible for both the IPhone and Blackberry, I think one of the reasons might be because the Blackberry App World has not been around for aslong as the Apple App Store.
But if you are looking to socialize I have found a few that have proven to work quite well:
Ping Chat - You can communicate using an IPhone, Android and Blackberry.
Liveprofile - You can communicate using an IPhone, Android and Blackberry.
You might want to wait untill someone more usefull has popped up and gave you an answer but from what I know there are no games that you can play on both IPhone and Blackberry.