Facebook users with smart phones like Droids or the iPhone can already use mobile versions of Facebook.But if you're among the 50% of Americans who still use a regular cell phone, you can keep up with the Facebook action too. The answer is Facebook Text Messages. By registering your phone for Facebook Text Messages, you can receive messages regarding your friends' activities, right on your phone. You can also send messages like status updates and wall posts back to Facebook. To enable mobile alerts, click Sign Up for Facebook Text Messages, then choose your country and carrier. Follow the on-screen prompts and wait for a confirmation message to appear on your phone. Once you've received the confirmation, enter it on screen. Be sure to notice, too, that you can opt to have your cell phone number displayed in your profile. If you'd like this information omitted, uncheck the option here. Once you've entered the confirmation code, you can customize a wide range of options regarding your text message alerts, from the kinds of texts you receive to the times of day you receive them. To stop receiving text message alerts on your phone, you can either choose the Off option seen here, or simply text STOP to 32665, or FBOOK.