A new workaround has been discovered for AT&T Android smartphones that will allow the installation of Android apps from the Android Market that are otherwise not allowed by AT&T without the need for device rooting.
Turn off your phone.
Pop out the SIM card.
Turn your phone back on and connect to a Wi-Fi network.
Open the Android Market, search for, and install the previously carrier-blocked app.
Turn off your phone.
Pop the SIM card back in.
Turn your phone back on.
The method works for now, but will be inevitably patched by AT&T in the near future as it does not officially sanction sideloading applications and actively restricts its Android smartphones from doing so. PhoneNews.com discourages customers from purchasing AT&T Android smartphones for this reason.
This can also be accomplished by simply placing the phone in Airplane mode and then making a WiFi connection. No need to remove the SIM card.