What version of Outlook? What language?
Each item has a Parent property, which is the folder the item lives in. So
item.Parent = some MAPIFolder object.
The easiest way if you are using Outlook 2007 is to get the folder.StoreID
and compare it to StoreID of your default Calendar folder using the
NameSpace.CompareEntryIDs() method. If you are using CDO 1.21 or Extended
MAPI or a MAPI wrapper such as Redemption (
www.dimastr.com/redemption) they
all have equivalent methods.