For the space geeks on the blog

Pretty cool Shuttle launch scheduled for today at 2:01 PM EDT. You can watch it over at www.nasa.gov on the Nasa TV feed. What makes today's shuttle launch different from all the rest you ask?
Well today the Space Shuttle Atlantis will be lifting off from launch pad 39A at Kennedy Space Center. Most Shuttles typically launch from 39A, so this not at all unusual. What makes this flight special is what is going on at the typically vacant launchpad downrange, 39B. There the Space Shuttle Endeavour, not scheduled to actually launch on trip to the International Space Station (ISS) until June 13th, sits ready to launch within a few days of Atlantis should the Atlantis Orbiter suffer catastrophic damage during its flight and the crew require an in-space rescue. On normal flights to the ISS no Shuttle is kept on standby for a rescue. Should the Shuttle be determined to be incapable to return to Earth the crew would simply remain on the ISS until a rescue Shuttle could be sent up some weeks/months later.
On this mission, however, the Shuttle Atlantis will not have the opportunity to "hide-out" at the ISS. It is lauching into a much higher orbit, that of the Hubble Space Telescope, to perform one final servicing/upgrade mission before the Shuttle fleet is retired in 2010 to make way for the Orion project. If Atlantis is damaged the only hope for its crew would be a daring/stunning multi-day mid-space rescue, where Endeavour would manevour in close to Atlantis (while travelling at 35,000mph) , the two Shuttles would link their robotic arms and the Atlantis crew would shimmey one at a time down into Endeavour on a spacewalk.
Now obviously this is only just an emergency plan. The odds are it wont happen. But it is still interesting to see both Shuttles sitting out on the two pads at the same time - for the first and last time since they did during testing in the 1970s.

Good luck to the crew of Atlantis STS-125