In the earliest Windows 8 images, we saw Windows Live integration on the taskbar. In the far right corner, there's a user tile displayed. If you'd like to do the same on Windows 7, download Taskbar User Tile from DeviantArt user AngelWZR.
Once installed, your current picture will appear on the taskbar. Click it, and a menu appears which allows you to log off, switch users, and access the control panel. Right now, the mod only works if your taskbar is displayed on the bottom of your Windows desktop.