Well, I hope they plan on beta testing for longer than 2 weeks before the release (beta in mid november, release at the end of november).
Remember, the only group of people that 5.1 is really going to affect is business customers such as myself, and we have a lot more to worry about going wrong than the standard home users do.
There were a lot of problems with the release of 5, but think about more important systems running with a problematic A/V... exchange servers going down, sql failures, sharepoint corruption, in-house custom applications, etc.
I just wish they'd give us something soon so that we can test to see what breaks before getting it on production systems.