This found on the Official Google Blog:
A trademark is a word, name, symbol or device that identifies a particular company’s products or services. Google is a trademark identifying Google Inc. and our search technology and services. While we’re pleased that so many people think of us when they think of searching the web, let’s face it, we do have a brand to protect, so we’d like to make clear that you should please only use “Google” when you're actually referring to Google Inc. and our services.
