I have a tile with my wife's profile. When she say something in Facebook (for example) the tile starts to show in its back what she said.
I go to her profile and click the status. I read it and go back. I go to "What's new" to see the same thing and open it again.
After that I go to home screen by pression back button. The tile still show the notification and looks like is impossible to stop it.
In "Me" tile when I read the notification it stops to show in back tile.
Edit: My Phone is a Samsung Focus