This isn't the final official version of the Sprint Mogul Windows Mobile 6.1 firmware update—which probably means that it shouldn't be called "official"—but it has been leaked on WinMo dev sites. New features are Sprint TV, a larger Start Menu, speedier response and of course, Windows Mobile 6.1. If you're really dying for new features on your phone you can download and install it now, otherwise we'd wait until the final version is available within the next month or so. [PPC Geeks via WMExperts via Boy Genius]
Hardly the first in the wild. I've been running builds of 6.1 for months now. This is the first semi-official build, though, and it's got some definite issues. There's another newer build being played with, though, that's a little stronger. Looking forward to that one hitting my phone.