This post is from Matt Cutt’s blog. Matt is a resident Google-ite who appears to be a fellow collaborator on their search inventions (his name appear on patent applications as inventor). Here we go:

Okay, Brett Tabke decided to call it Update Jagger. Here are the ways that I’d use to contact us if you have feedback on Google search results:

Reporting spam in Google’s index
I especially want to hear about webspam that you see in Google. The best place to do that is to go to http://www.google.com/contact/spamreport.html . In the “Additional details:” section, I would use the keyword “jagger1″ (that’s “jagger” and the number one with no spaces in between).

Reporting non-spam issues or problems in Google’s index
Do the search that you’re interested in on google.com, then click the “Dissatisfied? Help us improve” link at the bottom right of the page. Again, fill in details and use the keyword jagger1 so that folks at Google can separate out feedback specifically about this update.

You think your site has been penalized
If your site is not showing up at all, and you recently had something like hidden text or hidden links on your pages, I would recommend doing a reinclusion request. I wrote up my advice on the best way to do a reinclusion request. Note that a reinclusion request won’t make much difference if our algorithms/scoring are what is affecting your site though.

You see a low-quality site that is running AdSense
If you run across a site that you consider spammy and it has AdSense on it, click on the “Ads by Goooooogle” link and click “Send Google your thoughts on the ads you just saw”. Enter the words spamreport and jagger1 in the comments field.

You want to talk about data center IP addresses amongst friends, or “update speculate”
Lots of search-related discussion goes on at WebmasterWorld, but bear in mind that you won’t be able to mention specific urls or searches on WMW. If you want to mention specifics to Google, I’d go with one of the ways above. Visit site if you want to have a Free IP Geolocation API

Hope that helps to let people know where to send their feedback based on what they see.