There's a checkbox in Setup -> User Interface that allows you to drag Accounts from list views to calendar & quickly create events. When you drag them, a "balloon" pops up with all the fields (mini page layout).
It's all nice and shiny when Event has no record types:
But as soon as you add record types picklists get empty.
I have default record type set up (both on the Profile and user's personal preference).
I can even display it in the balloon - makes no difference (renders as non-editable info, same like on normal page layouts but without "[change]" link).
I'm sure the picklist values are added to all rec. types.
No matter what I do - picklists always come out empty.
As you can see we want Type to be mandatory but effectively this cripples whole feature - blank value prevents saving so you have to go to "Edit more fields" (a.k.a. normal edit page).