Google has gone live with Patent Search, which lets you search through over 7 million U.S. patents. The search engine seems pretty robust, with a bunch of advanced search operators, including:

• inassignee: - Search only patents with this assignee (example: Google)
• ininventor: - Patents from this inventor (example: Edison)
• intitle: - By patent title
• patent: - By patent number (which allows you to see Patent Number 1 - AAXL AND OTHER ROADS, which helps locomotive engines gain traction while traveling uphill)
• uspclass: - By patent office classification
• intlpclass: - By international patent classification

You can also search by issue and/or filing date. The patents have been scanned in, with the scan using the same interface as Google Book Search, which means it has all the useful features of Adobe Reader with none of the bloat and crappy performance.

What I really love is the front page, which shows images from five random patents that change on reload. One question: What if this patent comes up randomly?
(via Boing Boing and The Google Blog)