A SpaceX spokesperson said on Saturday that "due to the instantaneous launch window, we are not able to recycle and re-attempt the launch today." While reiterating Musk's statement about the problem with engine No. 5, she added that NASA and SpaceX continue to review data.
The re-launch is now scheduled for 3:44 a.m. EDT on Tuesday.
The SpaceX Falcon 9 booster was to carry a Dragon capsule laden with supplies for the ISS. However, SpaceX has only launched its current booster once before, for a December 2010 test flight carrying a Dragon capsule into orbit and back again as part of NASA's Commercial Orbital Transportation Services (COTS) program. That launch made SpaceX the first privately funded company to successfully launch, orbit and recover a spacecraft.
Although NASA awarded SpaceX a COTS contract in 2006, this flight - despite it being an actual "useful mission" to the ISS - will be a test flight, only. If the flight is successful, SpaceX will then enter into a $1.6 billion contract for a dozen cargo flights to the ISS.
Watch the slightly depressing video of the aborted launch, below.