I own two laptops, and upgraded to Ubuntu 12.10 on both of them. On one of them, when I get to the login screen, I see a nice interface with the same background image as the desktop, and a nice transparent widget that asks me to choose a username to login.
However, on the other laptop, the b/g image is just gray and the login screen doesn't look as nice. The widget seems different too. Any possible reason this might be happening?