Just had The Source for lunch...
I had read a lot of things about it on this blog so wanted to add my review...
Overall impression: Great airy modern space, good wine selection, innovative first courses -but perhaps a little overpriced. If I'm going to spend that amount of money, I'd rather go to Cityzen or Citronelle, etc.
Highlights: Suckling pig appetizer, "Chocolate Purse" dessert, wine.
Lowlights: Service... our waiter was unable to answer one question about the menu, and constantly forgot to replenish our silverware. The Artic Char entree was mediocre, as were the tuna tartare cones. My colleague had the striped bass and said it was good.
I would go back, but it won't be a regular and there are places in DC that are better - IMO.