It's obvious that many review systems aren't designed to help an employee, but rather provide management with justification to make staffing adjustments while providing CYA cover to all parties involved. Sounds like Yahoo's is really no different in that respect.

I have a non-scientific suspicion that performance reviews are going to become the next industry "thing" that prospective candidates evaluate before joining a company. On par with evaluation of benefits, comp structure, etc.

We're aiming to improve perf evaluation in my company, and I'll actively promote that with prospective candidates when we begin to see benefit. We want to identify and reward top performers, and provide support to the bottom to enable them to improve. (We're driving toward a culture that views under-achieving performance first as a failure of management.) We want this to be a strength, and something that our teams use throughout their time with us.