The Mac User Group CoM has instigated a PlushForums trial.
PlushForums claim to be mobile-friendly, I'm finding the whole thing to be a total wank-fest at present. You can be a forum member yet can't access any content posted previously, not even your own. It all shows up with a padlock icon and a message reading "This content is for subscribers only."
There's no mention on the help/FAQ pages of how to become a subscriber.
Another big ol' FUBAR or WOFTAM.