On a fresh install of Windows 8.1, the '%userprofile%\Documents\WindowsPowerShell\Modules' folder is included in $env:PSModulePath. After installation of PowerCLI 6.0 I see that folder is no longer included. This breaks people who have installed modules under their Documents directory.
The problem is linked to Environment variables. A fresh install of Windows has a SYSTEM PSModulePath variable defined but no USER one. In this situation PowerShell appears to silently add '%userprofile%\Documents\WindowsPowerShell\Modules' to $env:PSModulePath.
If you create a USER PSModulePath variable then this silent behavior changes. The PowerCLI 6.0 installer does create a USER PSModulePath variable if one does not already exist.
This behavior is also called out near the bottom of this blog posting: https://www.sapien.com/blog/2012/05/22/psmodulepath-discrepancies/
I'm not sure what the best way is for the PowerCLI 6 installer to address this. Perhaps it can be added to the release notes at least.
To add to this, passing ALLUSERS=1 to the installation, still adds to the user environment variable.