I want to install sql server 2008 r2 edition in a cluster environment. Can I use Windows Server 2008 R2 Standard edition?
It looks like you need to go to Server 2008 Enterprise or Data Centre for clustering, or Itanium for that usage case. My assumption would be once you have the OS sorted, you need to ensure that you're running a version of SQL that supports clustering
So, to answer your question - Windows Server 2008 R2 Standard cannot be used for a SQL cluster