Gforge 4.5 is the FLOSS version of GForge, that most of us can download, install, for instance as Debian packages.
But for some users looking for “the” latest, most up-to-date GForge, there’s a risk to go test (and buy) a non-free version of GForge AS, the “proprietary” version made by the main initial author of GForge, Tim Perdue (through his company GForge Group). While having a new product developed by a company which contributed to the liberation of GForge is not necessarily bad, the problem is that this confusion hinders the momentum for contributions to the free code base.
There seem to be some movement in the GForge community these days, towards more dynamics on the development of this leading FLOSS project, which hosts so many interesting libre projects.
Update 2009/01/25 :Expect some announcement in the forthcoming days on this front. Roland Mas has just announced what I was more or less announcing in this teaser : FusionForge has forked been announced.