It's underway, I've installed a test version of the site and I'm currently porting everything that happens on the main site, over to the new one.
There aren't many significant changes to core, but some of the custom modules for WMS need to be refactored. This can take quite a long time, and in the case of the groups module, may force a re-write.
The new site will have a few new features, such as being able to upload pictures of any size and have them resized and cropped automatically for use in profiles, on stories etc. Also the groups system will either be replaced by the Organic Groups module, or rewritten from scratch (more likely.) Also I'm going to add event signup capability so that people can say if they're comming to Maths Cafe to help out, or to get help etc.
Also I'm going to try to get the site talking to central timetabling so that you can tell it what modules your doing, and then the site will have your upcoming lectures in a block somewhere. Also, this will allow us to find times when everyone is free for holding meetings etc.
Exciting times.