Unlike the iPhone, where apps can only be bought from the App Store, Android smartphones and tablets can get apps from anywhere: Google's Android Market, Amazon's Appstore, and even third-party publishers' stores like Gameloft's.
Until a few days ago, Android smartphones on AT&T's network were the exception.
What do you mean? Where did AT&T phones get their apps from?
An Android smartphone on AT&T's network could only install apps from the Android Market.
The official reason, given by AT&T, was that making you get all your apps from the Android Market "forces developers to be accountable for the apps they submit," and "minimizes the risk of malicious apps harming customers." Which is ironic in hindsight because "the mother of all Android malware attacks" didn't come from some dodgy third-party market, but the Android Market itself.
OK, so what's changed and why?
You can install apps from other app markets now. Heck, you could download a beta app from outside the Market and install it like you'd install software on a PC. Anything goes.
As for why? Apparently, AT&T's decided to "be more open," after all the "negative publicity" it got about this. AT&T rep Jeff Bradley would also like you to know that AT&T had your best interests in mind when it disabled a feature on your Android phone, and hopes you won't hold it against his company.
Does my AT&T Android phone let me do this?
I don't know. Mine does. The Samsung Infuse 4G apparently did before it.
How can I tell?
Unlike with operating system updates, like my Aria's earlier upgrade to Android 2.2 "Froyo," you won't be texted to download something for this. Instead, AT&T appears to be quietly streaming updates to your phone, without notifying you.
If you want to see if the upgrade's taken place yet, go to the Settings app on your Android phone, then tap on Applications. If your phone has the upgrade, there will be a new check box, called "Unknown Sources." If this box is checked, you can install apps from outside the Android Market.
Why would I want to do that?
Well, for starters, there's this place called Amazon.com, and I hear they give out a free Android app every day. The kind that would normally cost you money.
Yep. Check it out.
Don't thank me, thank AT&T. For finally doing what it should've done in the first place.
Jared Spurbeck is an open-source software enthusiast, who uses an Android phone and an Ubuntu laptop PC. He has been writing about technology and electronics since 2008.