I really like this application. Therefore I used the openSUSE Build Service to create some RPMs for it:
http://download.opensuse.org/repositories/home:/dassit:/Virtualization:/Management/
I've tested them on openSUSE 11.2 and Fedora 11.
I expect them to work on openSUSE >= 11.2 and Fedora >= 11.
Because OpenXenManager required gtk2 >= 2.16 they do not work on SLES11 (gtk2 2.14) and below.
From what I read from the project website, I also expect that they do not work on RHEL5.
Anyway, a link for the project website to the RPM repository is possibly useful for somebody.