I know many people have been looking for Facebook chat on their BlackBerry and BeeJive is the first to bring it to market. Its a shame that the latest version of Facebook for BlackBerry 1.5 does not have Facebook chat support but maybe upcoming versions will bring it. (2.0?)
If you need your Facebook chat fix now you can pick up the BeeJive IM beta with it included. After the trial the app is $19.99 or $29.99 based on if you want a device or lifetime license.