Update, Dec. 4, 2014, at 14:50 UTC: After a morning fraught with problems, the Orion launch was scrubbed for today and will be attempted at the same time tomorrow: 12:05 UTC (07:05 Eastern time) Friday, Dec. 5. The first problem was a boat in the red zone in the waters off the Cape, and after that was cleared the winds picked up, violating limits. The countdown resumed several times, but then a problem with fuel valves in the tanks held things up. Cycling the valves (essentailly turning them on and off again five times) cleared the problem for the liquid oxygen tanks, but not the liquid hydrogen tanks. The problem took too long to solve and the timer ran up against the end of the launch window, so the attempt was scrubbed.
NASA's Orion test capsule is scheduled to launch on a powerful Delta IV Heavy rocket at 12:05 UTC (07:05 Eastern) today. That's 5:05 in the morning for me in Colorado, so I figure there's a chance I may not wake up in time to see it. Just in case, I'm posting this article early and embedding NASA's UStream channel here so y'all have a comfortable place to kick back and watch for yourself. You can try NASA TV as well.
The launch window is more than two hours long, so even if it doesn't launch on time it may still go up today. The mission itself (rounding the Earth twice and then splashing down in the Pacific Ocean off the coast of Baja California) is four and a half hours long, so there's plenty of time to catch it.
As I hear more (and get some coffee in me), I'll update this post.