There is an add-in for PDMWorks Enterprise that you can load in to Solidworks, which now is included in the flyout menu with file explorer, design library etc. From this pane you can lock, unlock and get a file. Also you can view version information, lock information, state information etc.
You cannot:
-search
-change the state of a file
-view "Where Used" info
-view any files in the vault other than what you already have open in Solidworks
All functionality that is available in PDMWorks enterprise, just not in the Solidworks add-in. PDMWorks workgroup's integration with Solidworks is much tighter - in workgroup you can even drag and drop a file from the vault in to your active model, all from within Solidworks. No such functionality exists for Enterprise.