Scott at Edge of the American West decided to see whether he could track down information on changes in voter registration since the campaign got going in earnest. He has posted his information here. Democrats have gotten more new registrants in all states for which Scott could find data except for Alaska. In some cases, they have outregistered Republicans by considerable margins. Highlights (numbers are voters added between the first and second dates):
Colorado, Jan-July 2008: 13,352 Republicans, 66,516 Democrats, 23,437 other.Florida, Jan.-June 2008: 77,196 Republicans, 209,422 Democrats, 26,100 other.
Iowa: Jan. - Aug. 2008: 7,515 Republicans, 69,301 Democrats, -62,922 other.
Nevada: Jan. - Aug. 2008: 1,230 Republicans, 51,547 Democrats, 7,550 other.
North Carolina: Jan. - Aug. 2008: 20,363 Republicans, 171,955 Democrats, 123,605 other.
Oregon: Jan. - July 2008: -13,349 Republicans, 122,518 Democrats.
Pennsylvania: April - Aug. 2008: 289 Republicans, 98,137 Democrats.
It occurred to me that the Florida numbers might reflect Gov. Crist's decision to reinstate felons' voting rights. He made that decision on April 3, so it fell within the period covered by the Florida numbers. However, there still seems to be a process for the restoration of felons' voting rights, and it is not clear to me how long that process would take, and thus how much the numbers here would reflect reinstated felons, as opposed to other newly registered voters. So I'm not sure about that.
In any case, some data to chew on.