We knew that AT&T's the only major US carrier that's going to be able to take advantage of the iPhone 4S being a HSPA+ device, but it's kind of unexpected that Apple might help them make that distinction with a 4G network indicator in the status bar. Updated.
Update: AT&T confirms to us that Apple and AT&T "working together on this." Note that they're not confirming it's going to happen, just that they're working on it. So we'll see.
4G network is in the process of adding LTE coverage right now. So once AT&T's at the point where it can claim an LTE network, having a "4G" iPhone that's running HSPA+ could be a little misleading for customers, depending on the real-world data experience they get. [ThisIsMyNext]