I would have thought that interns being paid 80k is more of a sign than product managers being paid more than engineers.

You are wrong. Interns are paid 75% of starting salary and don't work more than a few months. Many of these people are a year away from entering the labor force. With housing costs it's hard to take home more than a few k.

Fair enough. So it's the 105k graddie salary that's the bubble signifier rather than the intern salary per se. Makes sense.

It actually doesn't. New grads at Google were getting ~$85k in 2006. By the CPI, that's ~$101k now. If "graddie" salaries were any less than that, wages would have actually decreased.

Where I work, engineers make the product. I'm noy sure what the other people do. I welcome the techno meritocracy.