Sure; see the Extending developer page. Providers/datasources are really easy to implement. If you come up with a new one and feel comfortable sharing it, send it to me and I’ll consider it for inclusion with the core release.
As long as the license is respected, that’s great. While DataSiphon was developed as a graphical application, the transformation logic (libDataSiphon, if you will), is fairly distinct, and could be used fairly easily to construct intelligent import capabilities for your application.
Open a bug tracker issue in the SourceForge project.
Open a feature request tracker issue in the SourceForge project.
E-mail and I’ll get it answered as soon as possible.