Purging Mailboxes in Exchange 2007

We all know how vastly different Exchange 2007 Management Console (EMC) is from Exchange System Manager (ESM) in Exchange 2003. The other day I had to test a migration for work and realized that I no longer have an easy ability to purge mailboxes through EMC just like I used to in ESM:

Under the hood, selecting Purge in ESM calls Exchange_Mailbox.Purge method.
In Exchange 2007, WMI is gone. So Powershell comes to the rescue.
After reviewing "Remove-Mailbox" reference at TechNet, it sounds like "-Permanent" should be piped when removing the user and that's it. However, things are not that simple.
If mailbox is already disassociated, then I can query a list of disconnected mailboxes like this:

Get-MailboxStatistics | ?{ $_.DisconnectDate -ne $null}

Now, I need to pipe the "Remove-Mailbox", but which parameters do I choose?
It took me some mocking around but it turns out this is what you need:

Get-MailboxStatistics | ?{ $_.DisconnectDate -ne $null} | `
 %{ Remove-Mailbox -Database "Mailbox Database" `
    -StoreMailboxIdentity $_.MailboxGuid -WhatIf:$false}