Over at Google Blogoscoped, they just noticed that the Google Q&A data is exposed in Google Spreadsheets. This has actually been out for quite a while, but it never got much press.
In my mind, this kind of application was always far more interesting than the Q&A onebox. It's nice to give people quick responses to simple fact-finding queries, but it's far more interesting to aggregate, mashup, and expose data that they can re-use themselves. The spreadsheet integration is just one example of that sort of effort.
In addition to the data, it's an exciting demonstration of what you can do with a spreadsheet product that is native to the web. There are a lot of people with big ideas about where this can go from here.
Regarding the question about which queries trigger the Q&A onebox: it's based on a corpus that gets updated over time; as the scoring functions and data coverage change, you can expect to see certain queries start or stop triggering over time. I assure you it's still under development.