Exchange 2007 Room Mailbox

To create a meeting room mailbox with Cmdlet:

New-Mailbox -Name 'My Meeting Room' -Alias 'MeetRoom01' -OrganizationalUnit 'domain.com/Users' -UserPrincipalName 'MeetRoom01@domain.com' -SamAccountName 'MeetRoom01' -FirstName 'Meet' -Initials '' -LastName 'Room 01' -Database 'MyExchange\SG\DB' -Room

To make the room auto answer accepting the invitation:

Set-MailboxCalendarSettings -Identity "MeetRoom01" -AutomateProcessing AutoAccept

To share the meeting room resources (e.g. calendar):

Add-MailboxPermission -Identity 'MeetRoom01' -User 'DOMAIN\Domain Users' -AccessRights 'FullAccess'