A WebmasterWorld thread has one post from one individual who said his banned site was automatically reincluded in Google's index. In short, he did not go to Google and ask for his site to be reincluded, it was done by itself.
Normally, if your site is delisted from Google you would ask for a reinclusion request. Then Google would review your site and accept your site back in or not.
In this case, Google seems to have reincluded the site automatically, after a one-year ban.
I am waiting on more reports in this thread to see if this happens often. I would suspect Google sets a date for automated review of a site that was banned, so reinclusion can be automated. But I have never seen it reported in a support forum.
Forum discussion at WebmasterWorld.
