OpenGroupware packages have been completely built on the build service for CentOS5, Fedora 9, openSUSE 10.3, RHEL 5, and SLES10. The Fedora 10 and openSUSE 11.x packages needs some additional work.
Initial testing on CentOS 5 seems pretty positive, after a:
$ yum install ogo-meta ogo-database-setup
Only glaring bug is that ogo-database-setup doesn't actually populate the database schema so that still needs to be done by hand:
$ cat pg-build-schema.psql | psql -h localhost -U OGo OGo
Then restarting the services gives you [as far as I can tell so far] a fully working OGo install.
P.S. Make sure your getting the most current packages from the repository. mod_ngobjweb in particular should be dated March 4th; with the previous version the web resources (icons, etc...) for the WebUI won't be found at the configured path.