As of July 27, 2010, several categories are requiring that you specify the new, more granular Item Condition values using the new ConditionID field. This is a mandatory code change for developers.
After July 27: New listings: If the new condition ID values are required, and you do not pass them in, the listing will fail.
Existing listings: If the new condition ID values are required and you try to revise the listing without passing in the new values, the revise will fail. For example, if you try to update price or quantity without also including the new item condition values, the revise will fail. The listing will continue to exist on the site, but it will not have the new price or quantity.