Thanks, Vince.
Marcus - Linking to the forum from the API documentation was a good idea - I’ve done so. The HMAC and SHA-256 are standards that can be applied in various languages. I posted a PHP example, but it can be done in other languages as well.
I’d be interested in seeing the commercial Google APIs you’ve been able to use with Yahoo Pipes - can you post/email a link to their API documentation?
Can Yahoo pipes construct JSON objects?