Two pictures and you'll get the idea:
These houses are located on the north end of Mercer Island in Lake Washington, near Seattle.
To make this political, it's possible to look up the owners of each of these houses (using the King County Parcel Viewer), and then see if they have made any political donations recently. From www.opensecrets.org, the owner of the new house in the middle made two $2,300 donations to Rudolph W Giuliani (R) this cycle, and had one of them returned (shucks, he wasn't the nominee). The owner of the house with the sign has made a few Democratic donations, including $2,300 to John Edwards and $500 to Al Franken.
I must admit that - as entertained as I am at the whole schadenfreude - I'm a bit conflicted as to pinning the tail on any individual jackass in this situation. The new house is quite modern (check out the archtect's conceptual drawings here, look under "Graham Residence"), but I don't hate it and it isn't out of the ordinary for a lake front house in that area. Yes he's a repug, yes his sign wheeling neighbor is a democrat who "is deeply committed to worldwide philanthropic and environmental efforts, donating 5% of {his company's} pre-tax profits to conservation and educational groups" (the internet is so cool).
But I can't help thinking that putting up that sign isn't really the best way of dealing with this situation.