[Overgrow]

From the Google Webmasters FAQ:

What is cloaking?

The term "cloaking" is used to describe a website that returns altered webpages to search engines crawling the site. In other words, the webserver is programmed to return different content to Google than it returns to regular users, usually in an attempt to distort search engine rankings. This can mislead users about what they'll find when they click on a search result. To preserve the accuracy and quality of our search results, Google may permanently ban from our index any sites or site authors that engage in cloaking to distort their search rankings.

http://www.google.com/webmasters/faq.html


I'm assuming what you mean to do is give the spider a different page than a user gets if they click through from the search results.

That is Link Cloaking and that is grounds for banning, no matter how similar the pages are. Do at your own risk.