CPU upgrade on MacBook Pro I'm thinking about upgrading the CPU in my MacBook Pro from its current 3210M dual core processor to a 3632QM quad core processor.

Is there any reason why this wouldn't be a good idea? The socket, operating temperature, instruction set, wattage, and memory specifications match perfectly.

It's a summer 2012 production model, 13" unibody, FCPGA988 socket, 4GB DDR3 1600 MHz RAM (upgrading to 8GB shortly), with 10.8.3.
While Intel may produce versions of that processor that use an interchangeable socket, all Mac laptops (and almost all other laptops) have their CPUs soldered directly onto the logic board. This means it's effectively impossible to replace them, unless perhaps you have some high-grade industrial soldering knowledge and equipment. You can see this in iFixit's logic board replacement guide for your MacBook Pro.

In addition to that, I'm not aware of anywhere that you can buy individual Intel mobile CPUs. Because they're only used in laptops, they tend to only be sold to OEMs.