The Exchange Server documentation team announced new and updated Exchange Server 2007 documentation content. You can read the full post here.
With regards to PowerShell, there are two updated help files for Exchange 2007 SP1:
This download contains a standalone version of Microsoft Exchange Server 2007 SP1 Help.
To view the most recent version of the Help file within Exchange Server, extract the Help file (exchhelp.chm) to the folder where the Help file is currently installed (typically C:\Program Files\Microsoft\Exchange Server\Bin).
The Microsoft Exchange Server 2007 Exchange Management Shell Help file (Microsoft.Exchange.Management-Help.xml) helps you use cmdlets in the Exchange Management Shell to perform day-to-day administration of Exchange 2007. You can view help in the Exchange Management Shell by using the Get-Help cmdlet. Extract it to C:\Program Files\Microsoft\Exchange Server\Bin\<Lang>.