How can I tell when Turbo Boost is active on my MacBook? I have one of the core i7 MacBooks, and I'm wondering if there is a way to see when Turbo Boost is active (other than the fact that the laptop gets really hot and the fan kicks on). 

I use iStat to monitor CPU activity, but that doesn't show Turbo Boost activity.
Check out the Intel Power Gadget. It provides info about the processor frequency in GHz and Processor Power in W.