My project uses Gurtle too:
http://code.google.com/p/facebooksteamachievements/
For more information:
http://code.google.com/p/gurtle/wiki/ProjectsUsingGurtle
The project BlueMSX-wii uses it now too
[http://code.google.com/p/bluemsx-wii]
My project uses Gurtle too: http://code.google.com/p/sencille/
I'm really happy with his functionality.