I get to work with a lot of different clients and client environments and like many companies they are often running mixed versions of SQL Server. This can make things challenges when doing training since if some folks are missing service packs, etc.. They can get mixed results in BIDS or see things slightly differently. I was in the same situation the other day at a client and we could not find any consistency between the different lab machines the students were using. What is was trying to figure out was if they were running a pre-release beta version that may have had a bug we were trying to get around. This site was extremely helpful!
Also for all the versions check out
As always check us out at BIDN.com for more great information all around SQL Server, SharePoint and Business Intelligence.