I think it would be a ridiculously bad idea for Ron Paul to run in 2012.
Here's why: Ron Paul could have, I insist, won in 2008. However, every person who had access to the campaign management team at the time confirms that they were massively incompetent, contributing to Ron Paul's loss (although of course the moral failure of the GOP leadership had contributed as well). There has been no evidence of some kind of reorganization in Ron Paul's staff, or a change in his message. There's no evidence, in other words, that his campaign do stuff better this time.
In the previous election, Ron Paul has managed to perform what I insist is a political victory - gathering and organizing a political movement out of the people who supported him in the primaries, training them and bringing them together to support other candidates who went on to win - Rand Paul being the most popular, but others include Justin Amash.
If Ron Paul continues to run for President, and - most likely - fails yet again to get nominated, he would squander a lot of this political capital. Remember that failed candidates usually get less and less votes if they run again. c.f. Ralph Nader.
A Ron Paul run would be made even more difficult this year by the existence of candidates like Gary Johnson, who would siphon off at least some of Ron's support.