Unwanted Angry Birds Icon

Have an iMac running Snow Leopard and wife has a phone that syncs with the iMac... Anyhow, my son noticed an App Store update for Angry Birds and proceeded with the update. However, the update seemed to have placed this random icon in the bottom left of the screen. The icon is not selectable, cannot be dragged, dropped and does not open Angry Birds... it just site there and I can't get rid of it. Important to note that the icon is NOT in the Dock, not in the desktop folder and doesn't go away when changing the wallpaper. Doesn't seem to hurt anything but I want to remove it but cannot. I'm sure there is a way to remove it but I've already tried the ones obvious to me.

Thanks for your help!