Update #1 9/6/14: It looks like at least some of those who've run out to buy the Moto 360 at retail are already seeing the KGW42N update. Charge your watch, set it up, and you should get the alert.
Thanks to reader Justin for the tip and the photo!
Update #2 9/9/14: The G Watch is now receiving 4.4W.1 as well, though the build number varies slightly (KGW42Q):
Thanks, Devin Arthur.