We have a class/lab environment where the need arises to completely reset a user's mailbox, i.e. delete all mails, calendar items, ... and preferably do this via a script, whether it be in wsh or powershell or something else doesn't really matter.
My colleague attempted this in the past, but it required him to delete the mailbox, and then adjust settings in the registry somewhere to reflect the new unique id of the mailbox so this was too troublesome to do.
Our environment is an Exchange 2007 server in a mostly Win2003 domain (2003 DC's)
EDIT: I'd like to stress that everything from the "profile" should get removed, including calendar items and tasks!
Try the Export-Mailbox cmdlet with the -DeleteContent switch parameter.
http://technet.microsoft.com/en-us/library/bb266964%28EXCHG.80%29.aspx