It's been approved for quite awhile now. A friend of mine had it done and still holds a 1st class. It hasn't, however, been approved by the military yet. Supposedly they are concerned that it could rupture during an explosive decompression.
BTW, this topic might be better off in tech-ops. You may get a few more responses.
Right rudder....Right rudder...Come on, more right rudder....Right rudder......Aw forget it, I quit!!