The official trailer for The Sarah Connor Chronicles has shown up on YouTube.  The trailer can be found here.  (1:54)  Among the goodies: clips of the series, more info on Summer Glau's role as Cameron (and a little unfortunate acting on her part delivering a certain famous line), bits of data on the concept.  It's a trailer.

Things that are good: it's pretty and clearly the producers are paying the FX folks a mint.  Everyone's good-looking and most of them can act.

Things that might be problematic: see "line delivery."  Also, Thomas Dekker's John looks like he's being written as less "smart-mouthed but brilliant kid who'll make an unlikely savior" and more "emo man-pain guy complete with pretty brooding."  This could be a completely wrong assessment, and I will wait until I see the series before judging further.

Additional clips here and here.  Kinda disturbing clip here.