The web domain 'rainbowsix-bd.com' has also been spotted and was staked by Ubisoft in '09, and amended last year. Rainbow Six: Vegas 2 retailed back in '08.
Sean Popejoy's LinkedIn profile says he "developed Pro Tools sessions from Ubisoft audio for the game demo of Rainbow Six (2011)." This news broke on NeoGAF, with the same person also spotting Ubisoft behind the rainbowsix-bd.com domain.
Do you want Tom Clancy's Rainbow Six to return?