The tweet is worded a little differently from the Facebook post. The Facebook post says "Can you guess what it is?" The tweet says, "Can you guess what it is from this photo?"
So, it's a sign, in storage somewhere, showing the CBS Eye in front of the KYW call letters.
My guess: CBS news at the top and bottom of the hour (the one-minute casts at :31). It would explain the weekend debut. Time for the kinks to be worked out before morning drive Monday. KYW has debuted other changes over the weekend, such as refreshed jingles, before running them on the weekdays.
Will this mean Traffic and weather together on the 8s like WCBS-AM? They'd have to move it off the 2s because the first natural break in the CBS top of the hour news is at :03. Sports could stay at :15 and :45, business could stay at :25 and :55.
Wonder if the Osgood File and other CBS features might be added at :40 after.