One of the major benefits of owning an Android handset is the ability to install applications from non-Market sources — without the necessity of a dev-team intervention. AT&T customers have not, however, been privy to this particular feature… that is until now. In a letter to developers, the carrier has confirmed that it will, from this point forward, allow users to install Android apps from third-party sources such as the Amazon App Store. The act of installing applications through unofficial channels — oft referred to as side-loading — has been disabled by AT&T since the introduction of its first Android handset. The carrier’s newest Android offering, the Samsung Infuse 4G, was the first device to ship with the side-loading handcuffs removed and, thankfully, it looks like it won’t be the last.