The buzz surrounding the upcoming Motorola Droid Bionic got a little more intense Monday when speculation rose that it might not only be headed to Verizon Wireless, but also AT&T. If true, it could be one of the first 4G smartphones available on AT&T’s fledgling LTE network, scheduled to make its debut in five markets this summer, and expanding to 10 more by the end of the year. Until now, Verizon Wireless has been the only U.S. network associated with the Bionic, but what appears to be a leaked, internal company document – in the form of a company screenshot, published first by IntoMobile – would indicate that the phone could also become available through AT&T.