If you take a look in HotScripts under PHP there's four Weblog/CMS's - EZ homesite, PHP Nuke, php CMS, phpWebSite in the most popular block. Of these I've used 3 and I think PostNuke is better and should be up in that block.
I think getting rid of the nukish name might help. It would help differentiate it from phpnuke too which is a good idea. Being associated with something and someone (its developer) so buggy isn't good marketing.
I don't mean change the name today, quick! but I think it would be a good idea to do it sooner than later.