From Flame Trench here:
NASA could still pick up its original 2008 schedule after launching Atlantis on Jan. 10. A five-week turnaround between the launches of Atlantis and Endeavour would make that possible.
"If we launched on the 10th (of January), it does not affect the ability to launch on Feb. 14," said NASA spokesman Kyle Herring.
A Valentine's Day launch of Endeavour will return NASA to the schedule the agency proposed to complete the space station before the shuttle program ends in 2010.
However, if Atlantis' launch is delayed until Jan. 13 or 14, that would force a day for day slip in Endeavour's Valentine's Day mission. Laboratory modules will be delivered on both missions to the International Space Station.
"All of that still fits," said Herring.