OK, it's outing myself on a forum where I hadn't planned to, but I'm one of the Google employees on the other end of those contact forms, and I have regular access to the team that takes care of this sort of stuff.
First off, please DO NOT republish a link to any Google search results on this thread.
Secondly, will anyone who's been affected by this problem please use the contact form at this link to get in touch with Google:
http://www.google.com/support/bin/request.py?contact_type=remove_info
Ignore the stuff at the top of that page that talks about the webmaster, we make exceptions for credit card numbers. Please put the words "RPGNow" or "ENWorld" or "Swack-Iron" or something else I'm going to recognize in the subject line and me or one of my teammates will pick it up from there.
Only contact Google if you
know your credit card number is out there. If you don't know or aren't sure, just perform a Google search on your credit card number.
Finally, keep in mind that if Google got it, there's a decent chance that Yahoo, MSN, and any other number of search engines did too. I can't help you on those fronts.