I hate to be the barer of bad news but what Wilfred1 said is completely correct- this is the definition of "cloaking" - that is sharing different info with google then you do with a regular visitor and it is 100% against Google's most sacred rule. If someone reports your site YOU WILL GET BANNED FROM GOOGLE- and you may never get back on, if you do it will take at least 1 year. There is no appeals process, there is no debate- when Google confirms cloaking you are removed... period... the end.., Honestly everyone would be using this if that wasn't the case. Imagine if you had to register on every site you ever found in google before seeing the info you wanted.
Ask a "SEO Expert" if you don't believe me but this is common knowledge on the 'net.
http://www.google.com/support/webmas...y?answer=66355
http://www.google.com/support/webmas...n&answer=35769
If anyone cares about Google I strongly urge them to read the links above, search for "Google Anti-Cloaking Policy" and stop using the updated version of this mod immediately. You can not show different content to googlebot then you do any other visitor.