Three: Further instructions
Learned: Locke, Eko, and Desmond, but not Desmond's clothes, survived the hatch
implosion. Locke has a vision - led by the spirit of Boone - that some polar bears are holding Mr. Eko and he sets off to rescue him. Desmond has developed precognitive abilities. John Locke is dedicated to rescuing Jack, Kate, and Sawyer next.
Flashback: Locke. Locke used to live on a dope growing commune and accidently brought an undercover cop into their midst. This proves Locke is no fun at parties.
What do we know about the others: What others?