I just had this happen and found the fix. Thought I would share it for anyone having the same issue. I posted this in the Prevail section but figured a lot of you wouldn't see it there so I posted it here too.
This was copied directly from Google's site.
"Error processing purchase" on free apps Reported 12, June
We've had a few reports from other users of an "Error processing purchase" on all download attempts. We're currently investigating a more permanent solution, but in the meantime, please try the following to resolve the issue: - Navigate to Menu > Settings > Applications > Manage applications (on Android 4.0 devices, Settings > Apps) - Navigate to the "All" section - Scroll down to find an app called Google Services Framework - Select Google Services Framework, then tap Clear cache and Clear data
(Google-6/14/12)
This was copied directly from Google's site.
"Error processing purchase" on free apps Reported 12, June
We've had a few reports from other users of an "Error processing purchase" on all download attempts. We're currently investigating a more permanent solution, but in the meantime, please try the following to resolve the issue: - Navigate to Menu > Settings > Applications > Manage applications (on Android 4.0 devices, Settings > Apps) - Navigate to the "All" section - Scroll down to find an app called Google Services Framework - Select Google Services Framework, then tap Clear cache and Clear data
(Google-6/14/12)