Scott, I did the same in all my installs of wordpress, but the one with the actual problem had the issue hidden in the wp-config.php file. As I mention on my last post that file was the one allowing the "attackers" to break all other installs of wordpress, and no matter how many times I updated and reinstall WordPress on it, the issue was still there. I have to manually fix the problem with wp-config.php.
To be safe, I would suggest you to check all your installs and make sure the wp-config.php file is not infected. If you have a wp-config file with more than 100 lines you may have a problem.
Again the infected file has about 4000 lines and somewhere in line 2090 is where I found the pingnow funtion.
One thing I noticed about the wp-config file was that the "salt keys" was the same as the wp-config-sample.php.
Just be really carefull modifying that file and good luck!