There have been several popular television programs with Steampunk aesthetics or themes.
Riese is a Sci-Fi/Fantasy web series which debuted on the SyFy channel in 2009. The series follows Riese, who wanders Eleysia with her wolf, Fenrir. It has since been renamed Riese: Kingdom Falling.
There are several anime programs featuring Steampunk, including D. Gray Man and Last Exile. Also, Steampunk Culture was featured in an episode of the TV series Castle entitled "Punked".
There is some argument whether Joss Whedon's Firefly "counts" as Steampunk, since it's really more of a Science Fiction Space Opera. Either way, the show clearly shares some Steampunk style and costuming.