1: Magic items have levels. This probably has little to no in game effect, but it is a LOT easier on the DM. Previously, a DM had two ways he could figure out if an item was appropriate for his characters. He could tap his vast DMing experience and make a judgment call, or if he didn't have vast DMing experience yet, he could look at the cost, cross reference the wealth by level table, and try to backwards engineer information about when the item should be available. Now he can just look at a number and know WOTCs view on the matter, which is a LOT easier on new DMs.
2: The level of a magic item is the determinant of its cost. Ok. I'm not sure this will majorly affect anyone's game, to be honest. Consumables are probably costed separately for reasons I'm sure we can all figure out.