Hi Guys,
I am an ex Google Summer of Code student who began the implementation of MPLS in FreeBSD in 2008. I have managed to get basic sending/receiving and decoding of mpls packets working at this stage, but due to finishing university and moving into the big world of commercial development I havent had a chance to work on it in quite some time.
If you want any information on it here are a couple of links:
MPLS in FreeBSD wiki page
Perforce Repository for MPLS
The wiki also has a link to my FreeBSD blog which has a lot of the info on the project from the weekly updates etc I was posting for GSoC, and if you are really interested, there's even a dissertation I wrote on it for university that has the most details in terms of the project.