NHL 12's demo has been released on the Xbox Live Marketplace and Playstation Network.
The teams available are, of course, Boston Bruins and Vanvcouver Canucks. Not sure on the exact length but you get to play the third period of a play now game this year
.You can start a Hockey Ultimate Team as well. Then also you can test out the Be A Pro Mode.
A lot of plublicity for NHL 12 this year because they are some major changes this year. Everything is "live" and can be impacted (you can run over Bobby Lu). Also the physics and the overall feel of the game has significantly changed this year.
Try it out before the September 13th release.
EDIT: Pretty crazy that Robert Luongo is a 90, whereas Tim Thomas is an 89 and Thomas outplayed Luongo in the playoffs.