There was an earlier teaser that made Frozen look like a slapstick comedy. However I think Playbill has the first real trailer for this new animated Disney film. Playbill notes that it stars Idina Menzel, Jonathan Groff, Kristen Bell, Josh Gad and ... Alan Tudyk. Glee fans, Veronica Marshmallows, and Firefly fans, you should recognize these people.
P.L. I will say this is not some attempt by Disney to cash in on the WInter is coming GOT meme; Frozen is based on Hans Christian Andersen's The Snow Queen and has been in development for over a decade.