Okay, before anyone goes any further, there are SPOILERS here for both trailers/upcoming seasons of both True Blood and Game Of Thrones. You have been warned, okay?
True Blood - Season 5: No actual clips in the 30 second trailer, but the caption of 'Nothing Stays Buried Forever' could mean a lot of things. Russell's not due for the first few episodes and Salome is the main villain for the new year, so perhaps it's her the trailer is alluding to more. Plus, there's more antics in both the fairy and were story lines this year to contend with as well.
Game Of Thrones - Season 2: This minute long trailer certainly has a lot of spoilers, including Joffrey upping his cruelty towards Sansa, Arya pointing out that anyone can die, Daenerys aiming for her birthright, Catelyn turning on Littlefinger, Jaime tied up, Tyrion giving Cersei a fair warning about her people and other fun stuff. If anything, Season 2 looks like it's gonna be ten times more addictive than the first season will be and it's the show we're getting sooner as well.
Game Of Thrones - Season 2 Trailer: http://www.youtube.com/watch?v=rOzXsqoJhtE
True Blood - Season 5 Trailer: http://www.youtube.com/watch?v=EzcX-vCOFis
Game Of Thrones Season 2 will air on HBO/SkyAtlantic from April 1st/2nd and True Blood Season 5 will air on HBO from June 10th.