More questions I'll keep trying to give my take on...
Can I link from my blog to content or data within a RIA app?Can you link from your blog to content or data within a browser app? Only if that content is being served somewhere over HTTP or some other common protocol.
Same is true with a RIA app.
Flash sites where links can go out but they can't come in?Your choice. AJAX is the same way.
An AJAX app can run in a browser and display things that are not served by links to other clients, so can a RIA app display things that are not served by links to other clients.