NASA's Shuttle Atlantis Rolls into Place Answered
From the NASA homepage:
"Space shuttle Atlantis' rollout to Launch Pad 39A at NASA's Kennedy Space Center in Florida has been rescheduled to begin at 4 a.m. EDT on Tuesday, March 31 [today], as preparations for the STS-125 mission move forward. Atlantis is targeted to lift off May 12 to service NASA's Hubble Space Telescope.
...During Atlantis' 11-day mission, the crew of seven astronauts will make the final shuttle flight to Hubble. During five spacewalks, they will install two new instruments, repair two inactive ones and replace components. The result will be six working, complementary science instruments with capabilities beyond what is now available, and an extended operational lifespan for the telescope through at least 2014."