Merit Matters is starting a new series of blog posts looking at the differences between standard and actual costing in Dynamics GP. The first post is up at Costing in Dynamics GP 10.0: Standard vs. Actual Costing with more promised.
Dynamics GP 10 Standard vs. Actual Costing
Off-Topic & MiscellaneousGP 10
Archived post from 2009. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.