After 18 months of the JBoss Rules name for the product, Drools name for the project, my gut feeling is the split is contrite and only causes confusion - something that Marc Fleury also expressed at the time.
The Drools brand was much stronger than expected, most sites use the two words together "JBoss Rules/Drools", "JBoss Rules aka Drools", "JBoss Rules (Drools)", looking at Jobserve shows both words are used in all adverts - this to me shows a confusion in the market, with little advantage from the dual branding. Some places still use just Drools, this is also pushed by competing vendors that leach from us and want to hide any JBoss association - although this is undesirable it is still happening and causing confusion; there isn't much we can do to improve that situation, so might as well ride the wave - otherwise we risk something worse, lose of brand association of Drools with JBoss. On that note several vendors upstream what we do, none have given a single line of code or documentation back to be project; which is a pretty sad state of affairs, they obviously feel it helps their bottom line to include the software, yet won't lift a finger to help improve it - shame on you.
JBoss Rules as a name is poor for building a community, as it's too formal - people wouldn't like to say "JBoss Hibernate" or "JBoss Seam" all day, it's fine as a title or in the opening sentence, but then you want to switch to the informal name, otherwise it gets tiresome. Drools makes a good name space naming, and a prefix/postfix naming convention for classes. It's a single word and single syllable, making it easy to aggregate into other product names - "JBoss Rules BRMS" is a bit of a mouthful "Drools BRMS" is much easier.
There is of course those that don't like the Drools name, for its childish innuendos, and I did consider re-branding to something like DRules. I feel however that a further name change would be weak, and just cause even further confusion, especially with the strength of the Drools brand. So that would just have to be something we learn to live with :)
For these reasons, and many more I didn't mention, I am considering using JBoss Drools name for the 4.0 release. Feedback welcome :) even if it's just a +1 with your choice, to help me better guage public opinion.