Heh, Heroforge isn't
OGL legal as it is. All those extra classes, prestige classes, races, etc. Very little (read none) of it is in the
SRD.
WotC has kindly let it slide, as 1) no one is making a profit from it. It's totally free and is developed, tested, and distributed by volunteers. 2)
WotC has no competing product. If they did I'm sure they would do everything they could to stop HF. (And other more 'technically' legal communities that allow users to share their self made data sets.)
It should be interesting to see how the unlicensed char gen utilities fare with the birth of the
DDI.