Palin will definitely help McCain in states with the largest numbers of wackos. But those states were going to McCain anyway.
The Obama campaign remembers the biggest lesson of 2000: it doesn't matter who gets the most votes. What matters is who gets the most electoral votes. And with that in mind, this list of voter registration changes, via Hilzoy, is good news.
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.
What do you know? The AP is on to this, too.