AT&T is expanding the availability of its myWireless Mobile app to a couple of new Android devices - the Samsung Captivate and the HTC Aria. The app lets wireless subscribers manage their accounts from their mobile devices. The app give users access to bill payment, voice and data usage information, the ability to add or remove features and plans, and paperless billing. "myWireless Mobile is one of our most popular apps with close to four-and-a-half million downloads to date,