In a poll released a couple of days ago by Public Policy Polling, Ron Paul has emerged as the leader among prospective Iowa voters. Paul is polling at 23%, trailed by Mitt Romney at 20%. Newt Gingrich, who was the front-runner in Iowa a few weeks ago, has taken a hit in the polls recently and is currently polling in third.
A recent New York Times article notes that the Paul campaign has essentially been in place, but dormant, after he dropped out of the race in '08. The veteran volunteers, along with a web-based calling system, have helped keep the campaign organized in Iowa.