tedster - 4:51 pm on Mar 21, 2012 (gmt 0)
unless you got a message from Google via webmaster tools that you've been removed I wouldn't ask google to reinclude you
Important change - Google now calls it reconsideration requests, not "reinclusion' requests. It takes some pretty spammy actions to get totally kicked out of the index, and lowered rankings (penalties) are much more common.
If you have corrected the guideline violations that you feel caused the ranking drop, then a reconsideration request can be a good step, especially if rankings are not rebounding on their own. Just note - you must make a good faith attempt to repair the situation first. And also note, if your site and its entire profile hadn't received a manual inspection before, it certainly will now ;)
Here's a video with some helpful tips: [webmasterworld.com...]