With the help of posts from crobb305 and others, I was able to remove a hijacker's page from the Google index.
My site was doing very well in the SERPs. For over 2 years it had been on the first page for a competitive term (1.2 million listings). Then during the first week in January my site disappeared and traffic tanked for no obvious reason.
When searching for "site:www.mydomain.com" I noticed that my index page often wasn't listed or it appeared on about page 3 or 4 of the results after all my supplimental pages.
A search for "allinurl:mysite.com" often didn't show my index page at all but instead showed somebody else's domain (located in Turkey). When I clicked on this link, my site came up. When I clicked on the cached version of the site, it showed a very old cache of the page. This same site also showed up after all my results when doing a "site:www.mydomain.com"
Using a header checker tool on the site's URL I was able to see it was using a 302 link to my site.
Last night after reading some posts by crobb305 and others I went to Google.com and clicked on "About Google." Then I clicked on "Webmaster Info." Then I clicked on "I need my site information removed." Then I clicked on "remove individual pages." Where I found instructions on how to remove the page.
(Here's the exact page where I ended up. If mod needs to remove then snip away:) [google.com...]
I then clicked on the "urgent" link.
1. I signed up for an account with Google and replied back to them from an email they sent me;
2. I added the "noindex" meta tag according to their instructions and uploaded it to my site;
3. Using the instructions to remove a single page from the Google index, I added the hijacker's URL that was pointing to my site. (copy and paste from the result found on "allinurl" search)
This didn't work the first time because I had to remove a space from the url to get it to work.
4. I got a message back saying that the request would be taken care of within 24 hours. The URL that I entered showed on the uppper right hand part of the screen saying "removal of (hijacker's url)pending."
5. I then removed the "noindex" meta tag from my page and re-uploaded it to my site.
This morning the google account still shows the url removal as "pending" but when I do "site:" and "allinurl" searches the offending URL is gone and my index URL is back.
Conclusions and Speculations:
At some point last September, Google cached the hijack page's url pointing to my site. In January, Google penalized my site for duplicate content because it found both URL's and compared them. Mine got penalized because it was the only page that really existed. The hijacker's page didn't get penalized because it only existed as a re-direct to my site.
Because my index page was now penalized, it dropped almost completely from the SERPs. (Some of my suppliement pages showed up for obscure searches) but none of my money terms.
Because I haven't been able to get a response from the hijacker's webmaster, the 302 is still in place but it is buried deep in his site and the last Google cache of the page was sometime in September. Therefore with some luck Google won't re-index it any time soon.
Will my site return to the SERPs? I don't know. Any thoughts?