I've been testing this lately as I've not been timed out in an account for well over a week now.
It seems that if you login to AdWords through a Google account and not through your normal login, you no longer get timed out as you're in the same account.
Of course, if you have a business Google account (or multiples), a personal account, an internal marketing account, etc - then you'll be timed out if you're in personal GMail, business froogle, and internal marketing analytics, etc.
Overall, a nice improvement however.
Also means on a shared computer you'll want to log out of your google account before you leave the computer.