Angry CLIQ XT smartphone owners have filed a federal class action lawsuit against Motorola, Inc. (NASDAQ: MMI), claiming that the cell-phone maker promised people who bought its CLIQ XT smartphone that it would update the phone’s Android operating system, but it never did, making the phone “obsolete” and unable to run the latest versions of Facebook, Gmail and other popular applications.

Plaintiffs in the CLIQ XT class action lawsuit say that when Motorola released the CLIQ XT in May 2010, it was running an Android operating system that was already a year old. They say Android version 1.5, released in May 2009, is still the only option for the phone, even though Android 2.1 was available when the CLIQ was released, and even though Motorola promised, through tweets and posts on customer support pages on its website, that the phone would be eligible for an operating system upgrade.

The CLIQ XT Android OS class action lawsuit cites an October 2010 tweet by Motorola: "We are currently working to upgrade CLIQ and CLIQ XT to Android 2.1 in Q4. Apologies for any confusion."

Four months later, however, Motorola announced on its customer support page: "After comprehensive testing of the Android 2.1 upgrade for the CLIQ XT, we have concluded that this device will remain on Android 1.5."

Motorola’s failure to update the CLIQ XT’s operating system has significantly hindered the function of the device and quickly made it obsolete, the class action lawsuit says.

"The current versions of many of the most popular Android mobile applications available today will not work on Android 1.5, including applications such as Facebook, MySpace, Gmail, Angry Birds, Dropbox, Google Maps, Google Goggles, Kindle, Wells Fargo, USA Today, CNN, Yahoo Mail, YouTube, Groupon, MSNBC, Fox News, NY Times, NPR News, My Verizon, Blockbuster, QuickOffice Pro, and numerous others," the CLIQ XT class action lawsuit states.

Had consumers known that Motorola’s CLIQ XT smartphone would be stuck with an old operating system and they would be unable to use these Android apps, consumers would not have purchased the device, the lawsuit says.

The CLIQ XT operating system class action lawsuit is brought on behalf of a proposed class of all individuals and entities in the U.S. who purchased a Motorola CLIQ XT prior to February 2, 2011. It is seeking class certification, restitution of all revenue Motorola derived from sales of CLIQ XT, and more for violations of the Consumers Legal Remedies Act and Unfair Competition Law, False Advertising and Negligent Misrepresentation.

A copy of the Motorola CLIQ XT Android OS Class Action Lawsuit can be read here.

The case is Elyse Wood v. Motorola Mobility, Inc., Case No. 11-cv-04409, U.S. District Court, Northern District of California, Oakland Division.