Related question - can you use spring attack during a charge action, assuming you only move in a straight line? How about ride by attack? I assume the answers are the same, and yet it sounds like you're not allowed to combine the two, even though combining the two makes perfect sense in the traditional jousting match type situation.
Oh and on the main topic - I believe the restriction on movement should only be for movement during the charge standard action. The FAQ may say otherwise, and if a DM wanted to go by that, I could understand, but it doesn't seem to make sense, nor is it supported in the rules in the book.
-The Souljourner