Niklas Heidloff is being very productive today on the CompApp wiki. He just uploaded another page called Pass Context to Components when opening Composite Applications. On this page he explains a new url type (cai:///):
"Opening a connection to a CAI URL will cause the corresponding application to be projected to the client or updated if already on the client, and then opened in the user interface to the specified page. If no page is specified, the first page in the application is opened."
Besides being, as Nathan describes it, "hideous", it's never going to work IMHO. This approach fails the number one test for URL's - they should be easily computable and/or written by users. How something with an appInstanceID of 63 characters (example: CFB7535080ECD4C270FDD126C5DD9E27_11_5JMPDRH1000980269G784H2GO4) came through QA I don't know.
The page refers to M5 (probably milestone 5 for 8.5) and says that "we might publish [the url type] in Lotus Notes 8.0.1". Let's hope not!