From whence these came originally, your guess is as good as mine, but if Ubisoft is trying to keep screens of Assassin's Creed III secret, they're doing a poor job. Three of these screenshots depict Connor sneaking around a battlefield as Yanks and Redcoats trade fire. You get a look at the game's HUD for the PS3 version, too. A fourth appears to be a cutscene, some commanding officer addressing the troops.
Assassin's Creed III Leaked Images [All Games Beta]
(Note: Images appear as they did today on the site All Games Beta)