Just found this (via DCist via Capital Spice): it's a Google Map of the places that will be staying open late for Inauguration Weekend - the ones with 4 am last calls that can serve food 24 hours a day. Of course, this just means they're able to, not that they will necessarily. It looks like only Rumberos (which I had a terrible experience at) will be open in the neighborhood, but that U Street is the place to go.
The map might not be perfect, as I asked at the Big Hunt yesterday and the waitress said they would be open late, and there are also about 70 places whose applications to serve late are still pending - they have to get permission from their neighborhood's ANC, because they're under "voluntary agreements" where they aren't allowed to be open past a certain time. I think Wonderland might be under one of these - I'll do a post soon about which local spots will be open late.