In Windows 7, you can now use a slider widget to set UAC to four different modes. The first mode is the full-blown Vista behaviour; all actions initiated by any user requires you to pass a UAC prompt, including the screen blanking feature. This is the way UAC behaves in Vista SP1, and I'm probably one of the few out there, but it's the one I prefer. I like to know when something I'm about to do apparently messes around with important stuff.
The second setting is the default in the build handed out at PDC: administrators will not see a UAC prompt with user-initiated actions (elevations happens automatically), such as messing in the Control Panel. Programs initiated by the admin user still require a UAC prompt, but there's no screen blanking. Non-admin users will get UAC prompts for both types of actions, but there's no screen blanking.
The third setting means no confirmations will ever appear (admin users automatically elevate, even for program-initiated actions). The fourth and final setting disables the automatic elevation feature, so this is essentially Vista behaviour, sans the screen blanking.
I'm personally a proponent of the full-blown Vista SP1 behaviour, because it gives me the insight of what's going on, and it informs me of the possible consequences my actions could possibly have. However, this is a very personal issue, and I am sure that users will rejoice massively over this easy way of manipulating UAC behaviour in Windows 7.