You could already search through patents at the USPTO (US Patent and Trademark Office), however this search is clunky and not well organized. Google's Patent Search looks like it searches the entire body of the patent claim, not just the title, and the information is better organized for human reading. Here's the patent for PageRank, for example and the same info from the USPTO.
Just for fun, I ran a search for the term "Google" and found a patent for a swimsuit with attached "googles." Oops.
You will soon also have the ability to download and print patents in Google Patent Search, since US patents are public domain. Google jumped the gun and announced the features too soon, but they've since edited the Official Google Blog to reflect that these are pending features.