I work in Pittsburgh, and recently learned that my employer can own intellectual property that I created on my own time in my home. I was appalled.
It's not something to be appalled about. They aren't trying to be evil overlords.
Not so fast. A lot of East Coast companies aggressively enforce contract provisions, EMC being one of the worst.
If it's in your contract, and it's not illegal in that jurisdiction, you should be very concerned.
Most companies require board-level approval to change a contract, and you will usually be told, "I want you to leave the premises now."