Just registered the domain name RuleGoogle.com I plan on turning the website into a sales page offering an ebook on how to rank well in google. Thought it was an ok domain name so I had to purchase it.
Registering famous trademarks is not something you should do - it's trademark infringement and makes a domain worthless (actually less than worthless because it exposes you to litigation).
The only reason I purchased this ebook because it goes along great with my ebook "Rule Google" or "Search Engines". Thought it was a perfect fit for my ebook so I went ahead and purchased it.
It's still trademark infringement and can be taken by Google anytime they want. While some trademark holders will sue you without notice, Google will likely send you a letter requesting you to turn over the domain before proceeding with a UDRP action (at least that seem to be their history). I would just drop the domain and make sure you don't put adsense on the domain as it is also a TOS violation.