Win7 x64, GTX 590
Broken: (Latest Build from today Feb 17 hash tag: cc7cfd6)
Worked: Official Blender 2.69
Short description of error
You can see Rigify dev tools on every tab all the time, I don't know if this is a feature of rigify but is not visible on the oficial 2.69 release..
Exact steps for others to reproduce the error
Just look at the toolbar and you'll find Rigify Dev Tools option wich says: "Enconde mesh widget to python"