It appears that Roy Nelson and Shane Carwin will be undergoing extended drug testing for their bout at The Ultimate Fighter 16 Finale in December. Nelson posted a press release on his site talking about the testing:

Las Vegas, Nevada - A heated rivalry between two of the sports hardest-hitting heavyweights will be settled on Saturday, Dec. 15. Dr. Margaret Goodman and the Voluntary Anti Doping Association (VADA) is offering their service to Roy Nelson and Shane Carwin to clean up the black eye in combat sports with it's testing for performance enhancing drugs. Roy Nelson has already signed on with VADA and now awaiting Shane Carwin's commitment.

The Score reports that Nelson confirmed Carwin's participation in a media meet and greet yesterday. Their bout will be the second to use VADA testing, coming just one week after the welterweight bout between B.J. Penn and Rory MacDonald, who have agreed to use it as well. We reported last month that Georges St. Pierre and Carlos Condit have apparently agreed to extra testing for their November 24th bout as well, but they couldn't figure out who would handle the testing.

Additional drug testing is absolutely a good thing for the sport, and it's great that more and more fighters are willing to step up to the plate to participate.

UPDATE - Originally I wrote that the the press release above was from VADA. I was informed this morning by a VADA representative that they did not write the press release and don't know who did. Nelson has submitted an application to take part in VADA testing for his next fight though.