At the moment, it seems that (almost?) no one has the TV out cable. According to gp32z.com, they're expected to ship in 1-2 weeks (they've been delayed due to manufacturing issues?).
At any rate, the TV-out cable will plug into the bottom of the GP2X and will output 720x480 video (regular TV... probably NTSC?), which may or may not be scaled up from the 320x240 screen.
The outputs are s-video + stereo RCA jacks for audio. You can make the cable longer with s-video and RCA extender cables.
Hope that helps!