Looks like a Spruance giving "The Finger" :-)
Seriously, it's (and I quote)
Quoted Text
(Source: This ThreadThe Advanced Enclosed Mast/Sensor. It's more than just low observability and sensor protection, it's an integrated electronics system designed with modularity and ease of adding things like planar arrays. The theory is that the Spruance was the testbed for the mast to be used in the LPD-17 class.
Apparently the ship is being inactivated from regular service in Philly, and will then be towed to Pascagoula, MS, where Northrop/Grumman will use it as a testbed for several of the DD(X) systems such as the Integrated Power System, Composite Deckhouse (Whatever that is), and a dual-band radar.
Would make an interesting subject to do. :-)