SharePoint 2010 Column and List Validation

Another interesting feature I have found with column and list validation.  This feature works as described, but unfortunately only for NEW items.  If you enable column or list validation AFTER items have been added to a list, you will get an annoying error telling you the item was updated previously.

This does not happen on a new item addition.  Basically this means you have to create all your columns and validation BEFORE you start adding any items to that list/library!