A list of all calendars a user has access to

Hi All, 

My situation is as follows, I would like to create a report that will provide me with a list of mailbox calendars where a specific user has permissions and what permissions they have. A simple task, but one that keeps delivering me a roadblock. I haven't started the second part as I keep hitting this wall. 

Heres what I've come up with so far: 
get-mailbox -resultsize unlimited | get-mailboxfolderpermission "${$_.Name}:\Calendar" | Where {$_.User -like "Some User Name"}

For each mailbox in $mailboxes it spits out the following error: 
The input object cannot be bound to any parameters for the command either because the command does not take pipeline input or the input and its properties do not match any of the parameters that take pipeline input.
    + CategoryInfo          : InvalidArgument: (MailboxName:PSObject) [Get-MailboxFolderPermission], ParameterBindingException
    + FullyQualifiedErrorId : InputObjectNotBound,Get-MailboxFolderPermission

What am I doing wrong? 

Running this on Exchange 2010 SP3 / Powershell Version 2.0

Thanks