Aristotle and Dante Discover the Secrets of the Universe by Benjamin Alire Saenz...tons of amazing hype surrounding this book!
Etiquette and Espionage by Gail Carriger...new Gail Carriger series - woot!!
Eleanor & Park by Rainbow Powell...I've read Powell before and really enjoyed her writing AND this book is getting rave reviews (see Asheley's great review from Into the Hall of Books)!
And lastly Ex-Heroes by Peter Clines...I got this recommendation from the Books on the Nightstand Podcast and the premise of superheroes in a post-apocalyptic world sounds interesting.