But if you respond to a notification for market updates then it seemingly randomly goes to any old account. Some speculate it's alpha (that fits for me), others speculate it's the last account that had activity like email, talk, calendar, etc., others think it's strictly random.
To me it always defaults to my wifes account (which I only sync to borrow her contacts as she is the 'master phonebook'). She does gmail way often than my gmail but i'm not sycing here emails so there would be no activity on the device. But for me she is alphabetically in front of me. So thats my guess.
anyway work around is do NOT respond to notifications but only hit it through the app drawer until google fixes the bug.