Mike, w.r.t. http://www.programmableweb.com I believe this is a valid question, but I think that rich set of accessible APIs is more suited to the “mashup” phase of dataset-based application construction than the “meshup” phase.

To clarify: by “mashup,” I mean those applications that are constructed by marshalling functionalities exposed via web APIs. By “meshup,” I mean datasets that are constructed by combining datasets, usually published and accessed via #linkeddata principles.

Clearly the two can an must co-exist. I think the difference is that web APIs are expected to be specialized, but access to datasets should be in the first approximation uniform, allowing the specialization to happen (possibly, usually) int he specific vocabularies.

Then, given a standard approach to accessing data (like URLs, HTTP and HTML for web pages) communities can focus on shared vocabularies; see for example @iand’s OpenVocab project: http://open.vocab.org/