WB4 should have been based around QSSL's Neutrino kernel. But Fleecy screwed that deal by his wild accusations on Team Amiga ML. AFAIK, BlackBerry bought QSSL and perhaps use it in their new tablet but I have yet to read confirmation of this as a fact.
WB4?
Anyways, I ran Neutrino for a couple of years, and allthough it was nice, it suffered badly from lack of drivers (and lack of interest from QSSL to make drivers) and from native applications. The real killer was when someone ported GTK to Photon, and all developers moved to porting GTK apps from Linux to Neutrino. All the porting in essense killed native development, and none of the ported programs worked as well as they did on Linux/*BSD, so most users just left to use those instead.