As someone stated earlier, the fare exists from WAS too, for us DCA-based flyers (I can walk to the airport), it's a no-brainer near the end of the year:
DCA-IAH-EWR-POS-IAH-EWR-DCA is what I booked for US$364,20 with an immediate turn in POS, over the weekend. Easy, peasy (assuming security/customs have had enough MRers) and lounge access the whole way for some free snacks and drinks, if one isn't upgraded as a Gold+.
-jeremy