This is a very instructive question. You can see that much of these answers is the same stuff that people are saying on TV, and pretty much all wrong. People are just parroting non-information to each other.
Here's the reality: Pontiac is a big division, but they sell no trucks at all. Pontiac product development was combined with Buick and Olds back in the 1980's. They mostly badge engineered with Buick and Olds from then until the G6. It would seem stupid, to me, to say that Pontiac's problem is they sell Badge engineered Chevrolets. There was not much connection between their 3 main cars and Chevrolet, over the last 15 years or so. Complain all you want about badge engineering, but remember they sold a lot of cars. By definition, badge engineering is okay if you sell 200,000 of something.
So what's going on? This is my opinion:
What has actually happened to Pontiac is that GM management doesn't like Pontiac. They admit it to some degree. During the runup to the new Camaro, whenever Lutz was peppered with requests for a Firebird, he always responded with something that decoded to "I hate Firebirds - I don't want to do that"
They decided, some time ago, to develop products for Cadillac. They cannot afford to ignore Chevy, so they get new products too. Pontiac has to take scraps. This is an obvious corporate strategy. Starting with the G6, Pontiac now has to take Chevy-based stuff to fill the gaps created by lack of development. Pontiac does not have sufficient product development effort going into it to stay the size it was, which was huge, so it's shrinking. This is all just a matter of recent management priorities.
I have no idea what they'll be allowed to have in the future. I think the Solstice is great. I don't dislike the G6 at all, especially the retractable. That's a pretty distinctive product. I think the Australian cars are a great idea. Pontiac can get some good stuff easily from Australia, and it'll all be rear drive. They way they're built is just great. I'll take as many of those products as they'll let us have.
The G3, I can do without. The Vibe is a Toyota.
All you guys that brought up the Aztec, what was the Chevy version of that? Yuck. Distinctive is not always good.