The latest D&D Insider article by Stephen Schubert looks at the changed Skill DCs for checks, and also explains when you should use Easy, Moderate or Hard checks.
Interestingly, he suggests that if the first check in a Skill Challenge is Moderate, repeated checks should be Hard.
Cheers!
Interestingly, he suggests that if the first check in a Skill Challenge is Moderate, repeated checks should be Hard.

Cheers!