This might be slightly old news (though not too old), but HBO ran a 15 minute teaser for Game of Thrones the other day. As GRRM says, " This is NOT a trailer or an assembly of clips, but rather the first quarter of the first episode."
After having watched it, I'm more excited than ever. You get to meet the Starks (who all seem perfectly cast...except for Catelyn), get a glimpse of The Wall (which is awesome), and get a look at The Others.
I cannot wait.
It's supposedly on HBO's site somewhere, but you can also check it out if you like on Martin's blog:
http://grrm.livejournal.com/
You should know that, much like the books, this preview is gruesome. I counted 3 decaptitations...and all were shown.