Wild rumor turned into fact today as copy and paste is being slowly pushed out to certain developer devices.
The OS update bumps the version number to 7.0.7338 from the current 7.0.7004.0, which is also probably not the final shipping version. In fact, Conflipper noted back in November that they are internally up to the 7.0.75xx level already--so this is definitely early/incomplete. No other new features are noted with the OS upgrade, so this may be just an early tester version to get feedback on usage and stability from developers.
Of course once you finally see it in action, you're left a little crestfallen---almost a "that's it?" kind of thing. After all, this is pretty basic and boring stuff here. Still, such a small feature will go a long, long way for PR with our new OS.