James Fee notes that Swivel originally had a data api. (What follows was originally a comment I submitted to James' post but his MT installation appears to be having trouble.)
The API issue is interesting. I've also encouraged Swivel to provide an API and I'm sure they are going to release something very cool in this area. However, the more one thinks about it, the more the convergence of ideas leads me to the notion of the Data Web. This is an environment in which the data is distributed, discoverable, described and linked just as the text data of documents is now. One would have a data browser and a service like Swivel would be more of an aggregator/search engine rather than a data repository. Rather than data tools exposed through current browsing technology, there would be a data browser.
Note that I'm not talking about the semantic web here. I'll try to get my thinking together and provide a deeper dive on the Data Web soon. For now, this is also appropriate.