One of the rumoured changes coming up in Windows 8 is the availability of user profile in taskbar. Although not much details are available as of now, Deviantart user has created a simple freeware tool, Taskbar UserTile, which brings in the user profile into Windows 7 taskbar. The application is portable and just run the tool and it adds the user profile link to the taskbar.
Clicking on the image open a small popup which allows you to switch user, log off, Lock PC, open control panel and also change the profile image.
Although the tool is in alpha and comes with bugs, it definitely is an innovate tool based on the Windows 8 features.