I've received many emails on this topic lately, so rather than bothering to return all of those emails, I thought I'd just post something on the subject and save myself a little time...
A Christmas Eve buffet will be available from noon to 8PM. Menu is on the 2941 web site here. 2941 is not open on New Year's Eve.
Check out Equinox's Christmas Eve menu featuring many incredible options like Cream of Chestnut Soup, Maple Glazed Muscovy Duck with Leg Confit, Mustard Crusted Rack of Lamb, and Eggnog Ice Cream. It won't be cheap, but it'll sure be good. Full menu on the Equinox web site here. On New Year's Eve, a six-course tasting menu will be offered for...well, the web site doesn't say.
Bringing a traditional meal normally served in Italy on Christmas Eve to DC. From the Dino web site, "The Feast of the 7 Fish is is an all seafood meal that usually includes fried fish, seafood soup, ravioli and a whole fish." A limited version of their regular menu will be available as well. See the full "Feast of the Seven Fish" menu here which will be available the 22nd through the 24th. On New Year's Eve, Dino will be offering a five-course menu for $85 a person. I'd spend time describing the menu, but you can easily read how fun it sounds here.
Fahrenheit at the Ritz Carlton in Georgetown
Open Christmas Eve and Christmas Day offering a four-course dinner both days. Call (202) 912-4100 for reservations. They're also open New Year's Eve and Day, but no menu is available on their site.
Evening Star Cafe
Evening Star Cafe, one of my favorite restaurants in Virginia, is open New Year's Eve and will be offering a five-course tasting menu for $85. Their menu for the evening is on their web site here.