I wasn't aware that former NM Governor Gary Johnson was running for President in 2012. He would no doubt be a decent choice. I also see that his fan club is out and about here on RIA. More power to them--all the reports I've heard out of him is that he was a good governor. He lowered taxes, left the state with an almost perfect bond rating, and balanced the state budget in the process. I'd go out on a limb and say that 90% of the candidates on this list can't say the same. Johnson also ran the state with business-like precision; a quality which is sorely needed in Washington. I also appreciate the fact that he has experience in government at the executive level. Legislators in the final analysis usually make poor Presidents.
I think he'll take some of the Ron Paul voters, should he officially run. Also Johnson needs to get more aggressive in terms of publicity and making media appearances. He's not going to get a lot of votes if people don't know that he's running. If he plays his cards right, I can definitely see him in the thick of things. There is a lot of weakness right now in the GOP race; right now Mike Huckabee is leading the pack, so anything can happen.
The big knock on his chances for the nomination will probably include a lack of institutional support. Plus I don't see the rank and file lining up behind a pro-choice, pro gay rights, pro drug legalization candidate. Also not helping matters is the fact that he's been out of office for a few years and doesn't have a strong public platform.
In principle he's a good candidate, but he's likely a longshot. He might make it interesting though, especially if he plays his cards right.