The song that plays in the trailer is "Bones" by MS MR.
I have been rewatching the trailer since it came out last night, and it just continues to make me even more excited. Granted it's only a minute long, with not much telling about what happens (mostly not wanting to spoil anything, given that a certain event many are dreading yet anticipating this season), but it's still pretty awesome since it's a trailer with actual footage and pretty music. Also, Dany being gorgeously badass and dragons. *__*
The new season premieres March 31st.