I'm having the same issue on v6.0 R1 and cannot get this to work.
Get-Module -Name VMware* returns VMware.VimAutomation.Vds in the list, however add-pssnapin VMware.vimautomation.vds fails with the generic message:
add-pssnapin : The Windows PowerShell snap-in 'VMware.vimautomation.vds' is not installed on this computer.
I can load VMware.VimAutomation.Core without any issues but not the VDS module and therefore all VDS related commands fail when executed from a .ps1 script or native PowerShell, such as get-vdswitch and export-vdswitch.
I'm thinking about trying an older version of PowerCLI, just wanted to find out if anyone else out there has the same issue. I am trying to automate exporting our VDS switch configurations and am currently stuck.