I noticed that 3912 8th Street NW, which has had an "Under Contract" sign hanging from the Fairfax Realty sign for quite a while, now has a Vacant Property sticker on the window. Of course, that sticker really goes with the smashed glass of the security door and the pile of newspapers on the porch.
Also interesting, newly renovated and very expensive 703 Upshur St NW also got a nice bright yellow Vacant Property sticker on its window. Wasn't there on Sunday, I don't believe, when they had an open house. Oops.
More info on how and why the city considers properties vacant is available on the DCRA website.