Problem
In exchange 2007 and exchange 2010 by default microsoft does not allow users to create sub public folders within a normal public folder.So we need to enable them with a bit of powershell magic.
Resolution
Open up Exchange PowerShell and run this command to enable..
[PS]
C:\Program Files\Microsoft\Exchange Server\Scripts>.\AddUsersToPFRecursive.
ps1 Yourservername \ sales andrewd {publishingEditor}
Yourservername = your server
\sales being the public folder
andrew d being the user who you want to give rights to.