Hi Tina,
I am on the expert comittee (at least, on the second incarnation of it,) but I didn't have much input into the definition of the API. The reference implementation in the public review package is a Jess driver, which I wrote; this was my main contribution, to determine if the spec could be implemented. As a result, Jess supports this evolving spec and will continue to track its revisions. Chapter 21 of Jess in Action contains some javax.rules example code.
There has been a great deal of disagreement about the content of the spec among the committee members, and heated discussion is still ongoing. There are three major points of contention: one is whether the spec sufficiently takes advantage of other
J2EE APIs, or whether it is not well enough informed by them; second, whether the current focus on J2EE-like systems is appropriate (as opposed to a J2SE-oriented API with more extensibility); and third, whether the current API represents a generic rule engine API, or whether it only makes sense for a subset of the existing types of rule engines. It's not clear when these debates will be settled; it could be soon, or it could go on for a while, still.
My personal feeling is that standardization may still be premature, because there is still a lot of innovation going on. A cross-vendor interface necessarily goes to the lowest common denominator, and I know that in Jess's case, at least, this means that the standard API can't give you access to a lot of cool features. But in any case, I plan to continue to support javax.rules, wherever it ends up going.
