Possibly far more features than any other Wiki available, including embedded scripting within Wiki documents (a huge plus for me) and embedded Hibernation SQL/fulltext engine. Unfortunately, using most of these features in XWiki are undocumented for now. Definitely worth a look if you want something with a feature set on par with (or vastly surpasses) TWiki, but faster (Java-based, runs under Tomcat engine) and more dynamic like Zope.
Why not look beyond the 'big two' packaging systems?
In my opinion, the packaging system and tools (inst, swmgr) that comes with IRIX 6.5 is much better than RPM and DEB.
SGI enforces a fairly strict naming system which lets you very quickly select groups of packages for installation, removal, or update using simple commands. Tracking down dependencies is very slick, as well as the ability to manipulate 'subsystems' within a package. Perhaps SGI will decide to open source their tools at some point?