Google has been known to issue out all kinds of penalties over the years; even Search Engine Journal was penalized a while back (or our Google Toolbar PageRank was). In addition to Google PageRank penalties, there are all kinds of reasons to get penalized by Google which range from building too many obvious spam links to publishing duplicate content, hoaxes or untrusted material.
A site can always fix their problems, hold their hand to their chest and promise Google that they will not go down the same route again, and can then file a reconsideration request, asking Google to review the site and reinclude the site in the Google index or get their PageRank back; dependent upon the severity of the penalty.
But are you ever totally in the clear?
Barry looks at some discussions around whether or not Google actually totally forgives a site after it is penalized and feels that Google keeps historical records of site penalties which may lead to larger future infractions if a site breaks the Google Webmaster code of conduct again.
According to Matt Cutts, lying in a reconsideration request is going to result in the smashing of your site : “Don’t lie in a reconsideration request. Just don’t go there at all. Makes Matt *angry*! Matt smash spam!”
But I don’t see any published records of the amount of reconsiderations allowed or how they will influence your future rankings or chances for being penalized in the future.