Google Considering Notifying Webmasters of Some Penalties (Search Engine Guide)
”Web site owners have been clamoring for years over the idea of being notified when their site is removed from the index.
According to Matt Cutts, Google is not only starting to do this on a limited basis, they're actually planning on implementing this even more often in the future. I'll make note that Matt explains that the notifications are designed to go to web sites that are inadvertently doing things that might get them banned...not to notify all sites.
After all, Google has no desire to let spammers know exactly how close to the line they can come. ;) You can get the full story on Google's plans at Matt's blog.”