Xfce is my main desktop environment since more than 6 years, and I really like it. I try to make some patch from time to time, and if you search a project to contribute, it's here ;-)
The core team is really small (2 or 3 people), so development evolves rather slowly, and the 4.12 will be released when it is ready.
Here a little video with latest git version ( from http://git.xfce.org/xfce/xfwm4/ ). You just need to press ALT and scroll up/down to zoom in/out.
(yeah, it's an excuse to test the html5 <video> balise with ogv file ;)).
I will try to make some blog posts about new features in xfce world for the upcoming 4.12 (in 2014 I hope!), stay tuned !