RIM has been doing a wonderful job with updating users with the latest OS 4.5 releases. The latest release I have found online is the latest OS 188.8.131.52 Release 58.
I was just sent a link to the LATEST version 184.108.40.206 OS for the 8100, 8110, 8120, 8300, 8310, 8320, 8800, & 8820. Sadly there is still no CDMA version of OS 4.5.
One of the places the files can be found are here UPDATE: The cats already out of the bag. Just search online and you will find the links all over the place.
This is probably ready for official release since Vodaphone has already officially released 220.127.116.11 and Rogers is shipping out the 8120 with OS 18.104.22.168.
Once again download these at your own RISK!!! T-Mobile UMA users might want to stay away from the 4.5 downloads since they had issues with the last release.