As per the latest news it seems that Microsoft has released the SP1 Beta of MS Office 2010 to the testers.
It is not released for every tester,It is given to only pre-selected testers via the Microsoft Connect portal.
The full build number of this release is 14.0.6011.1000.
The size of this beta is approx. of 294 MB.
Currently we don’t have much info about this but we will keep you update in future.