I've read about nservicebus countless times on the net, but still don't get what a service bus is.
All I think is it is a way for very disparate systems to talk to each other? In which case, I don't see why it is any better than WCF?
I've seen the thread on here about what a service bus is but it still hasn't clicked.
Thanks
Assuming that you have read these pages http://particular.net/nservicebus and http://docs.particular.net/nservicebus/architecture/nservicebus-and-wcf you'll find that NServiceBus makes communicating with services much easier.
It wraps WCF by taking care of the poisoned and transactional elements of messaging as well as offering out of the box Pub / Sub style messaging. Benefits that NServiceBus will take care of include: