Windows 7's streamlined UAC.
By default (at least in the build given out at PDC), Windows 7 will show Administrator users many fewer prompts than Vista. No user-initiated action requiring elevation (i.e., changing a setting in Control Panel, creating a folder in a restricted location) will result in a UAC prompt. Instead, the elevation occurs automatically, allowing the action to succeed.
However, if a
program attempts to perform such an action, UAC steps in and displays a prompt. This provides a pretty good balance between annoyance and protection. Furthermore, the UAC prompts no longer black the screen out. Instead, they just appear as regular dialog boxes.
Read more at the source.
Later

Ted