Aisha was telling me that I said people are healed around him( I can never remember everything I say). First Sara, then everyone on the island, Locke, Rose, Charlie giving up drugs, Sawyer helping people more. The way he was talking to Jack in Season 2 when he ran away from the hatch. What does he know? I can't wait for his flashbacks!
I think the biggest thing that I want to know about Desmond right now is the reason he deserted his post or whatever while in the military. I'm betting money that it'll be due to Pen and the fact that it was either him desert or loose her. Or at least something along those lines.
I think his powers are going to be an interesting thing to see how they play out. I'm wondering if he'll know that Kate, Sawyer, and Jack are in trouble/maybe escaping?