There are several options available when looking at removing content from Google's search results. If you're willing to wait until the next time the search bot comes around, there are various methods (depending on the situation and content) to instructing the bot to remove/not index your content.
This process is explained here: http://www.google.com/support/webmasters/bin/answer.py?
For urgent requests, you can use Google's Webmaster Tools to expedite the removal process. This process, which will require site ownership verification, usually takes 3-5 business days and is explained at the following two locations:
Bing encourages the use of tags, as does Yahoo, however Bing also provides a way to request urgent removal.
Removing content from the Live Search Index:
"To remove or disallow content from being accessible through the cache, you can use the noarchive meta-tag or X-Robots-Tag. For more information please see our FAQ: How to Keep Your Page From Being Cached in Yahoo Search Results."
Yahoo also removes the cache when the page returns a 404 error.
"Content can be removed from the web by having the webmaster remove the page from the website so that attempts to read the URL return a 404 error. This also removes the page from the Yahoo Web Search cache. Pages that no longer exist are removed from web search results and from the cache after the web crawler refreshes content and notices the 404 status."
How do I have my website or web pages removed from the Yahoo Search Index?