Matt Cutts has some information about the Jagger Update, looks like some people are over at WMW trying to figure it out and provide us with some info. Googleguy on WMW says:
McMohan, good eyes in spotting some changes at 188.8.131.52. I expect Jagger2 to start at 66.102.9.x. It will probably stay at 1-2 data centers for the next several days rather than spreading quickly. But that data center shows the direction that things will be moving in (bear in mind that things are fluxing, and Jagger3 will cause flux as well).
Matt Cutts posted how to send feedback on Jagger1 at http://www.mattcutts.com/blog/update-jagger-contacting-google/
If you’re looking at 66.102.9.x and have new feedback on what you see there (whether it be spam or just indexing related), please use the same mechanism as before, except use the keyword Jagger2. I believe that our webspam team has taken a first pass through the Jagger1 feedback and acted on a majority of the spam reports. The quality team may wait until Jagger3 is visible somewhere before delving into the non-spam index feedback.
If things stay on the same schedule (which I can’t promise, but I’ll keep you posted if I learn more), Jagger3 might be visible at one data center next week. Folks should have several weeks to give us feedback on Jagger3 as it gradually becomes more visible at more data centers.
Matt indicates that you submit a reinclusion request to Google by putting "Jagger 1, Jagger 2, or Jagger 3" in the subject line of the email.
He also says, "Jagger1, Jagger2, and Jagger3 are mostly independent changes, but they’re occurring closely enough in time (plus they interact to some degree) that it’s clearer just to act as if they were one update for feedback purposes. "
Discussion at WMW