A Google-Sync-Daemon would be one solution, eg. not talk to Google via the Exchange protocol. That would leave the Exchange to beconfigured and used with your work account.
I'd like to see something like this as well since I'm in the same situation, Google on the private side and an Exchange on the work side. Having to decide for either/or regarding PIM sync is kind of a pity.
As pointed out earlier by others, combination of the PIM data is not really an option either.