As this has been a frequently requested link, I’m posting here.

Step by Step Guide to Building a Hyper-V Cluster

http://technet.microsoft.com/en-us/library/cc732181(WS.10).aspx

Information on upgrading a Hyper-V RTM cluster to R2.

http://blogs.msdn.com/clustering/archive/2009/10/08/9905089.aspx