I wish the business logic I may write in ruby could be accessable by other applications in my environment.
The minimal requirement should be SOAP. I would not really consider XML-RPC. As long as I am wishing the SOAP implementation should support complex objects.
It would also be great if the same objects could also be published via CORBA/IIOP.
If my wish came true then Ruby on Rails would be a legitamate contender to the java J2EE frameworks.
Discussion
Also interesting considering javascript applications is JSON-RPC.
It should be possible to build all these on the same backend.