If you know nothing about it, here's the scoop:
Joss Whedon's defunct FOX Space Western about a renegade crew 500 years in the future. FOX killed it mercilessly with poor advertising and by playing the episodes out of sequence. DVD sales were so huge that they gave Whedon $40 million to make a movie from the series, which comes out in September.
This is my favorite TV show of all time, it's smarter than Buffy and more mature than Angel. The characters are 3-dimensional and extremely engaging, and the show has Whedon's trademark wit combined with intense drama and action.
It's premeiring tonight on Sci-Fi at 7pm - they're playing all the episodes IN ORDER over the next few weeks. I highly recommend watching it!