JSonline blog from Haudricourt indicates Gallardo had swelling and pain in his knee after a recent throwing session. They suspect torn cartilage. If he's scoped, he'll miss 2-3 weeks according to Melvin, which would leave him about half of March (or more) to get ready for the season.
No idea how to do a link here, but you know where to go.
Update [2008-2-18 19:12:27 by battlekow]: link