This is nothing new - they do it to everyone that they detect as hosting malware. I cleaned up a clients site that was experiencing this about 8 months ago.
Agreed, I had a cleanup several months back myself. I must say that it's annoying how long it takes to get off the list, and surprising how quickly they add you. I cleaned up the site, but there was still a backdoor in a plugin file (necessary to the site, but written with heavy obfuscation by paranoid developers) that I missed and the site was compromised again. Soon as it finally started reporting clean it was on the list again.