Google's Android mobile phone OS is available on a handset from all the four major carriers. Mobile phone carrier AT&T has recently entered the Android arena with the Motorola Backflip.

Google is getting its Android OS on as many devices as possible, in contrast with Apple, which sells a single phone via a single carrier.

Google is offering its operating system free of cost to handset manufacturers such as Motorola, Dell and Motorola.

Google's first Android-based mobile phone, the Nexus One, runs Android 2.1, the latest version of the operating system. It includes full voice-typing support, free turn-by-turn navigation and live wallpapers free of cost.

However, the Motorola Backflip is still running Android 1.6 version of operating system and that too with several missing features.

Now-a-days, companies such as Apple, Google and Palm quickly upgrade their mobile phone operating systems with a view to add new features and fix bugs.