I believe Rio provided WebStart support in the past and I think it would significantly lower the bar to entry if it were provided again, particularly in light of the recent OAR support.

For instance, if Rio developers (i.e. not just committers) were to build OAR files for reusable services a user could launch Rio with a click on a JNLP file and then deploy a service by using a URL to a posted OAR. A new user discovering the Rio website could run Rio and launch a demo service in less than 5 minutes. Exploration of the technology, then, would occur through the Rio UI as much as via documentation.

My understanding is this would require almost no change to Rio itself. The difficulty is the requirement that all the jars be signed and thus the need to acquire a certificate.