The updatable help in PowerShell 3.0 caused a lot of confusion when that version first shipped. The help files have been updated periodically since 3.o shipped but its always been difficult finding out when they’ve been updated.
There is now an RSS feed that provides information on updates to the help files. Written by the team that creates the PowerShell help files you can now keep up to date with changes.
Subscribe at http://sxp.microsoft.com/feeds/msdntn/PowerShellHelpVersions.