I Think My Graphics Card Changed
Most recent 15" MacBook Pros have dual graphics cards — one integrated into the CPU (the Intel 3000), and one discrete card (the Radeon). It switches dynamically based on what programs are running and how they use the GPU.

Some more info from Apple:


MacBook Pro: How to determine which graphics card is in use
MacBook Pro: How to set graphics performance
MacBook Pro: About automatic graphics switching and OpenGL applications