To follow the 2008 Amgen Tour of California LIVE, your best bet is to use the Adobe Tour Tracker, which is simply amazing. GPS tracks the location of cyclists on an online route map, and a constant video feed with audio commentary puts you in the action.
For archived video footage, Steephill.TV is always good at posting links online shortly after the stages end.
On cable TV, Versus will provide recaps of each day's stages most evenings at 8 PM PST / 11 PM EST, with coverage during the weekend stages (including the prologue) beginning at 2 PM PST / 5 PM EST.
KWC may also provide some race commentary along with myself and a few other people for the FredCast cycling podcast, which will provide daily audio updates of the race. Watch also for live updates on the Tour of California from Steephill.TV. Watch this space also for updates, news, photos and video on the northern California stages.