OK, I had this problem for my name in a cached version of a facebook page.
In this regard, Google says :
"if you need to remove Google's cached copy of a page that has already changed on the website or stop Google from showing results for a page that has been taken down completely, you can use Google's removal tool to expedite the process. To use the tool, you'll need to follow certain requirements, detailed below.
...... you can request removal of the content from appearing as a cache copy or snippet in Google's search results by using the public URL removal tool. (It bears repeating: The site owner—whether it's you or somebody else—must have first made the required changes to the site, or this process will not work to remove the content from search results.) "
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the complete instruction is in the following link :
http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=164734
Go to the mentioned link. It explains the process of removing in detail.
Good Luck