The launch is of course subject to weather conditions and technical issues. The latest status may be found here:
http://www.nasa.gov/mission_pages/shutt ... index.html

As of now, the latest update with about 3 hrs 52 mins to go is as follows:
Space shuttle Atlantis' astronauts are donning their orange launch-and-entry suits in crew quarters and are set to depart at 7:36 a.m. EDT for Launch Pad 39A. The crew will begin boarding Atlantis at 8:06 a.m.
Inside the Launch Control Center at NASA's Kennedy Space Center in Florida, the launch team continues to closely monitor the weather. The forecast remains 30 percent "go" with a concern for showers and thunderstorms within 20 nautical miles of the Shuttle Landing Facility, flight through precipitation, and cumulus clouds. Liftoff time is 11:26 a.m. Teams are not working any issues that would delay the launch of Atlantis on mission STS-135, the final flight of the Space Shuttle Program.
It would likely be covered live by the major news channels, e.g. BBC, CNN, Fox News, CNBC. You could probably also get a live stream on the NASA TV website:
http://www.nasa.gov/multimedia/nasatv/
I can actually remember watching the launch and landing of the very first one all those years ago, that of the Columbia. And also waking up one day in Jan 1986 to the news on the radio that the Challenger had exploded.
Sigh... end of an era. I really like the Space Shuttle.