I have come across this term after long discussions with some coworkers in the last 5 years. As I study business necessities, create architectures and work together with developers on the implementations I am now so convinced about the power of this solution that I feel the need to share my experience.
A Business Hub (BHub) is an entry point to your business services. It is just the MVC pattern applied rigorously. BHub services are not necessarily SOA and actually in my implementations far away from SOAP. The services in a company are entities that accept input variables and provide output variables similar to what a quadripole* does.
In a BHub your Controller acts as a quadripole as well. It is in charge of processing input variables which might come the REST, XML-RPC, SOAP (you name it) way. It is again in charge of generating output variables (In a Java world just request attributes).
In a BHub your View decides how to format the response variables. The same entry point to your business services, the very same logic is applied, the same response variables are generated but the final result depends on the consumer: PC, home appliance, a partner application, mobile devices, spreadsheets, email, printer and more.
Flow or user states of course are reused as well. No matter if you use add-hoc code, Drools, JBPM, or custom Rules Engine your stateless controllers will become stateful at some point but that should never affect the final result.
BHub is MVC with an important statement, the architecture must be View agnostic.
So next time you pick your framework be sure you can configure it to get your BHub up and running with minimum effort. You will have no problems exposing business logic at any possible level.
* Thanks to Hector Gessa, my scientist friend, for the quadripole analogy.