I'd also like to add an "if-modified-since" support, so we can send GET requests but only have data sent back over the wire if it's newer than Revision X or some etag has expired, etc.

Agreed.

Why aren't we doing something to solve a problem w/ the current apps? For example, aggregating image info and article info together into one response?

If I'm not mistaken, the thought is that if this relatively simpler service experiment goes well, then it will make sense to go ahead with pursuit of the bigger composite service (and probably a suite of services in due time).