From today's WaPo :

Some of them may vote for McCain, but the numbers are nonetheless eye-catching. This year, 474,000 Democrats have been added to the rolls in Pennsylvania -- while the GOP rolls have actually lost 38,000 voters. In 2004, there were 357,000 Democrats added and 66,000 Republicans.

I will be interested in seeing what the totals are after today's registration deadline. Both sides have been making a big registration push. If you are a Republican, like myself, you should be very concerned.