After just making the latest PlayBook OS available last night/into this morning, RIM has pulled it because of issue connecting to the BlackBerry Bridge. Issues have been reported for pretty much everyone that along with upgrading the PlayBook OS have upgrade their Bridge app on their BlackBerry. For those of us that hadn't been prompted to upgrade BlackBerry Bridge, this latest update is working fine and has had no issues. So the simple workaround for the time being is to downgrade BlackBerry Bridge to 18.104.22.168 until the next PlayBook update is released "sometime this week".
We're working on getting some OTA's available for it so stay tuned but if you find one beforehand give it a try and let us know if it fixed the issue.
UPDATE: Download links added below. You must be logged into BBOS to download.