As of this post, Space Shuttle Endeavour is currently undergoing its final launch preparations — for its final mission, in fact. If all goes well, NASA will send Endeavour on the agency's 134th shuttle mission, where it will rendezvous with the International Space Station, carrying spare parts, pocket-sized satellites and other equipment.
Update: NASA just announced on Twitter that Endeavour won't be going up today after all: "Endeavour's launch has been scrubbed for at least 48 hours because of an issue with Auxiliary Power Unit 1 heaters."
The space shuttle Endeavour sat on Launch Pad 39A as a storm passed prior to the rollback of the Rotating Service Structure, Thursday, April 28, 2011, at Kennedy Space Center in Cape Canaveral, Fla. Endeavour launches on the STS-134 mission on Friday, April 29 at 3:47 p.m. EDT. During the 14-day mission, Endeavour and the STS-134 crew will deliver the Alpha Magnetic Spectrometer and spare parts including two S-band communications antennas, a high-pressure gas tank.