There is a very important note over on the WebmasterWorld forums today that all web developers/admins out there should probably take a look at.

From the posting: It is now 100% certain that any site can destroy low to midrange pagerank sites by causing googlebot to snap up a 302 redirect via scripts such as php, asp and cgi etc supported by an unseen randomly generated meta refresh page pointing to an unsuspecting site. The encroaching site in many cases actually write your websites location URL with a 302 redirect inside their server.

[...] Many unethical webmasters and site owners are already creating thousands of TEMPLATED (ready to go) SKYSCRAPER sites fed by affiliate companies immense databases. These companies that have your website info within their databases feed your page snippets, without your permission, to vast numbers of the skyscraper sites. A carefully adjusted variant php based redirection script that causes a 302 redirect to your site, and included in the script an affiliate click checker, goes to work. What is very sneaky is the randomly generated meta refresh page that can only be detected via the use of a good header interrogation tool.

It goes on from there, talking about a few things that you can do to try to avoid this issue and protect your site. There are also a few comments that project a worse scenario - one in which you might just have to talk to Google themselves to take care of the issue...