The two heavyweight contenders are headed for the ring. Online search-engine giant Google ( GOOG) has created a cellular-phone operating system called Android that is currently available in T-Mobile's ( DT) G-1 phone. They believe it is the rival of all the other leading smartphones currently on the market -- including Apple's ( AAPL) iPhone 2, Sprint ( S)/ Samsung's Instinct, Palm's ( PALM) Pro or Centro or any of the BlackBerry ( RIMM) devices. In this weekly series, I review the head-to-head battle of products while my colleague Scott Moritz handles the equity. Back to the tale of the tape: Google's Android mobile operating system has appeared on just one handset so far. Don't get me wrong, I like T-Mobile's G-1 (also known as the HTC Dream in other countries). But despite all the rumors circulating in the industry, the only other Android-based device actually announced (by the U.K.'s Vodafone ( VOD)) is another HTC phone just like the G-1, except there's no slide-out keyboard. Could this be the rumored G-2 coming soon from T-Mobile? The only other Android device I saw last month at the Mobile World Congress in Barcelona, Spain, was a non-working mock-up of a device from China's Huawei. It was in a display behind thick glass. They weren't crazy about me taking video of it or answering questions about it. The G-1 is a terrific smartphone. Not perfect, but terrific in its own right. The touchscreen works, the 3G is fast (it runs on T-Mobile's new network) and the Android App Store is catching up to Apple's in terms of numbers and quality of downloadable software.