It’s just a demonstration, so for simplicity, compactness, and flexibility the demo app includes a text editor that allows users to modify the saved data for each sample that supports it. But a real application would send or read the data from the server. You might want to watch the video where we use WCF RIA Services to exchange data with the server: GoSilverlight OrgChart using RIA Services
All of the demo samples use XML because that is what most applications use these days, and because it’s very easy to implement, but if you need to support some other XML schema or some other textual or binary format, that’s possible too.
Does that other application have a particular data format and schema that it expects?