I'm going to get this once it comes out. I have the UL30vt right now, its rated for 10 hours on, and if battery life is what you want, then you'll want the U36sd. I usually spend 12-16 hours at school, and I rarely bring my charger, but I do turn off wifi when I don't need it.
http://forum.notebookreview.com/asus...han-u36jc.html
here are some pictures, mind you it is the U36jc, the jc is the older model, sd is the successor with the same body shell 19mm thick!
http://www.engadget.com/2011/03/03/asus-u36jc-review/
if you don't want to wait for the sd you can buy the jc now at NCIX, but sd utilizes the new sandy bridge archi
http://www.ncix.com/search/?categoryid=0&q=u36jc