I've installed all my Domino test and demo servers in VMs running CentOS
6.x. It's very, very similar to the officially supported RHEL 6 ("aims
to be 100% binary compatible") and I had no real issues yet. 
Only one annoyance: I couldn't install
the Domino server in graphics mode, only in console mode. Today I've found
out why: I was missing a required package: libXp. A quick yum
-y install libXp and now I can
run the graphic installer. Yay! 
Source: Domino
8.5 - Required Linux packages and updates
