If you ride the Red Line, you may have noticed a new blue and black mural emerging on the side of one of the new buildings between NoMa and Union Station this week

After the Washington City Paper acknowledged the Black Cat near the top of the pack in its 2008 best-of category for dance clubs — right up there with monosyllabic sweat-halls Town and Love — the Cat had a crisis of conscience. For some time now, most Friday and Saturday nights have been guaranteed to be themed dance nights with names like Mousetrap, Bliss, Homo/Sonic, Cryfest, and CATatonia. That means choice weekend slots not reserved…