I really like the Add Multiple feature but wish that I could add folders, events, milestones, etc using this dialog. For example I need to set up a project where 5 of my developers are attending a training session. I'd like to add them all at once in batch. Or setting up my schedule to include all the company holidays for each person.

Perhaps extend the shorthand notation like you have done for task lists or allow me to put the type after the estimate. In some cases you might be able to determine the type by the estimate. If I enter a date range then the estimate is for an event. If I enter a single date it's a milestone.