First they raised the prices by 100% ~ 500%, with very little notice, then surprise, surprised, everyone stopped using it (well I'm guessing here, but what else could have happened?). Then they backed off a bit and made it cheaper only for their ad partners. So you could only use their API economically if you display their scummy ads and get their blessing. And now it's just cancelled. The alternative -- YPA -- is a client-side Javascript solution unusable on the server side.

No wonder Yahoo is in such trouble -- lately, they've taken good products, ruin them or stop improving them, then cancel them due to everyone abandoning them (Mail, Maps). Or they just cancel good products without trying to monetize them (Pipes).

I switched my search engine to use the Bing API and never looked back. It's a shame that it is the only top-tier search API available now.