I did urgent security patching on the forums, long overdue, took a few minutes longer than I expected, but it worked and thats what counts.
Some people have had issues getting the new forum to load, getting the frames but no fourm, this is most commonly because they are using a link which takes them direct to the old forum.
The fix is to delete your existing bookmark, navigate to the forum using either of the forum menu items (up top or on the left) and then create a new bookmark.
That said, things will probably change again as I upgade the Site again and reintegrate the forum with the rest of the site, that should happen sometime in the next week.