Although GM does own 20% of Subaru, Subaru does not fall completely under the GM umbrella. Subaru seems to be doing fine as a company, their sales for April were up 23%... giving them their best April in the company's history. But...
You can still buy a Subaru Impreza and get the GM employee discount. Although Subaru isn't under the GM umbrella, Saab is. And the new Saab 9-2x AWD sports compact is really a Subaru Impreza in disguise. Saab changed the schnozz, tightened up the suspension a little, and gave it a few interior refinements to distinguish it from the Subaru, but it's essentially the exact same car. And Saab is offering the employee discount on all models through the first week of July.