Exchange 2010 – build numbers and rollups

How do I find my Exchange 2010 build number?

Exchange Management console:

1. Start the Microsoft Exchange Management console.
2. Expand the Server Configuration objects.
3. On the right side, notice the Exchange version number.

Exchange Management shell:  

1. Start the Microsoft Exchange Management shell. 
2. Run the following command:

   get-exchangeserver
   or
   get-exchangeserver | fl

How do I find my Exchange 2010 rollup number/version?
Well that’s a different story; and one that is best described by the Exchange Guys here:
http://blogs.technet.com/b/exchange/archive/2010/03/08/3409469.aspx

Exchange build numbers and release dates.
http://support.microsoft.com/kb/158530