I would be up for building some StackScripts myself but I hate to have to buy a complete plan to do it. I really wish Linode would offer a more fine grained billing.
It's pro-rated to the day - so if you add a Linode for the month but remove it after one day, you've ended up being credited back all but $0.67, in the case of a Linode 360.
I agree. I'd infinitely love Linode if they offered hourly billing of servers.