UPDATE: Twitter for BlackBerry now officially available and ready for download. Pick it up in BlackBerry App World or download it OTA to your device at http://www.blackberry.com/twitter.
The official Twitter for BlackBerry client went into public beta back in April of this year. It was later updated to version 1.0.0.40 in May. Now that we are at the beginning of July, Twitter for BlackBerry is coming out of beta and will be officially released on BlackBerry App World sometime tonight.
It available now. I update it a few hours ago. Just go to options and then check for update.