The Request is definitely the 'big' feature in this release. Going to be great for promotion and reminding FB users of your site. Will take a little bit of configuring to get going (you'll see), but we think it will be well worth it. There's lots of other improvements there as well.
Documentation is being worked on now.. should have most up tonight with lingering stuff through the weekend.
Oh, by the way, JFBC 4.1 is in the download area now!
Let us know if you run into any issues. We test the hell out of everything before releasing it, but things find their way of cropping up when tons of people start pounding on it.
Good luck!
Alex