Are penalized sites reincluded automatically after a while?

... or are they banned from Google forever?

[tombola]

In another recent thread: Permanent Self Removal [webmasterworld.com], a member said that even if you deliberately remove a Web site from Google's index "Google will add the site back into their listings after 90 or 180 days. They will do that even if the site does not exist, or domain has expired.".

a) Is that true?
b) If true, does this apply to a penalized site too?

[tedster]

Lately the tool removal seems to last more than 180 days. Might be an issue with rolling out Big Daddy, I can't say for sure. If the domain has expired, it still might pop back up in the supllemental index for a while - at mleast that's the way it seems at the moment,

And yes, some sites that get penalized and then clean up the offenses begin to reappear "algorithmically". It happens gradually in steps, and not always all the way to their former glory. I'm not sure if this is a universal effect or something that Google is still testing in certain cases and not others.