We've upgraded SFN to version 4.1 of our forum software, and things are looking good so far. Take a look around and enjoy the new features, and post here if you experience any weird problems. Some things to note:
You may enjoy the new Activity stream, showing everything that's happening on SFN in real time (the page automatically updates).
There are some minor updates to the LaTeX rendering we now use, which are detailed in an updated thread in the maths forums.