Ran across a Facebook posting by Windows Phone saying "Our Live Tiles may be trying to tell us something". The posting pictures a magenta AT&T Nokia Lumia 900 with the Phone Tile is displaying "10", the Linked Inbox an "11" and the Messaging Tile a "12".
The obvious thought is October 11, 2012, which is today. But so far all is quiet on the AT&T news front. But many format their dates day/month/year which would put the date November 10, 2012. Up until this little riddle, the strong school of thought has the new Lumias landing on Sunday, November 4th. Which fits AT&T's launch habits (the 10th is the following Saturday).
We'll poke around and see what we can come up with but in the meantime, there's a discussion going on over in the WPCentral Forums on what this riddle could mean. Feel free to chime in and let us know your guess.