It's one of several 2-minute shorts commemorating Batman's 75th anniversary, I believe. It's brilliant but it's not a TV episode. You can find it on you-tube and yahoo video. It's probably also airing on Cartoon Network. It's a cruel tease to anyone who was a fan of the original series.
There is also another listing of it on IMDb credited to Bruce Timm. If you like Darwyn Cooke, check out the Parker series of comics. They are outstanding.
It appears to feature the original voice actors, most notably Kevin Conroy. And the theme music is there, too.
It's so short, hard to say more without giving away spoilers.
