You can export/import views as XML or CSV. The generated XML is UTF-8 encoded and it only has three element types in total for the cells and rows so the structure of the file isn't complicated at all.
Treesheets is an awesome way of structuring ideas and materials. As Matti said, the XML output from TreeSheets is easy to parse and convert for other uses. Basic HTML export is also provided as a simple means of sharing sheet data. Since TreeSheets is an open source project - it is possible to extend these areas of functionality to meet your own workflow needs and the code is easy to follow and fun to work with.