The song is called Let's Be Friends [Hit Me Up on the BBM] by the duo called Breeze and SP. It's reaaally catchy and the video is hilarious so I thought I'd share...
YouTube - Let's Be Friends [Hit Me Up On The BBM] **Official Music Video**
Enjoy! :D
Edit: Also, they actually have the ringtone loaded on CB, here's the link! :D
http://crackberry.com/ringtone/hit-me-bbm-breezeandsp