Wassim Fayed [MSFT] has published the source code for the Cmdlet Help Editor on CodePlex.
Cmdlet Help Editor enables you to create help topics for Windows PowerShell cmdlets and in the XML format that Windows PowerShell reads. Help text created in Cmdlet Help Editor can be displayed immediately by a Windows PowerShell Get-Help command without any additional transforms or formatting. By reflecting on a Windows PowerShell snap-in (PsSnapin) assembly amd modules, Cmdlet Help Editor creates a customized documentation interface that includes the cmdlets in the module, their parameters, and parameter attributes.
The first edition of the Cmdlet Help Editor was designed for Windows PowerShell cmdlet developers to make it easy to create cmdlet help. The second version added support for PowerShell V2 and scripters could use it to write help files for modules. Now that the source code is published on CodePlex the community can add its own contributions to it!
The latest version of the Cmdlet Help Editor can be downloaded HERE.