However, this seems like a very limited scope (possibly a good thing). Would the question be better as What versions of Java are supported and proven to work for Tridion 2011 SP1 HR1?. This would encourage answers listing all versions to be given- not just giving the latest version.
I guess someone could list all of the supported and proven versions in their answer, but I wonder if the question could be made more useful for future visitors.
You have the power to edit the question - it looks like people are giving those sorts of answers anyway but you're free to edit the question and leave a comment explaining your edits. I'd have said you have a good point.