It seems that the Macbook Air 2010 model has some issues waking from its standby mode which it goes into after an hour of on-battery sleep. I'm looking for a way to disable this standby behavior. I'm sure there's a plist file somewhere that will turn it off but I can't find it for the life of me. Anyone have any ideas/hints?
Caffeine will not stop the computer from sleeping when the lid is closed (this comes form experience, I use it daily), for this you will want InsomniaX http://roaringapps.com/app:1281
Naturally, if you still want it to sleep when the lid is closed, then Caffenine would be the better solution as detailed in the other answer.
You could just run Caffeine.
Caffeine is a tiny program that puts an icon in the right side of your menu bar. Click it to prevent your Mac from automatically going to sleep, dimming the screen or starting screen savers. Click it again to go back. Right-click the icon to show the menu.
To disable standby / "deep sleep", run the following command in Terminal:
sudo pmset -a standby 0
See this question for more information.