Henrik Walther has just published his part 2 on managing Exchange 2007 with PowerGUI at MSExchange.org:
In part 2 he goes through managing public folders, setting permissions, provisioning mailboxes from csv files, reporting, as well as extending the tool.
(Too bad these were written before we extended the pack to cover all the functionality missing in the native Exchange Management Console.)
Henrik’s posts are good step-by-step tutorials with lots of screenshots and easy to follow. Highly recommended!