Hi, module-rebuild lists both ieee80211softmac and bcm43xx, but unfortunately bcm43xx relies on ieee80211softmac to have been built and installed successfully to be able to build itself. This is perhaps a bug with that driver (which is admittedly very recent and experimental), however it should be possible to have module-rebuild use the dependency information from the packages it has to install, to determine what order is best to compile them in... It's hard to tell whether this is a bug or an enhancement, so I've marked it as an enhancement, however that are packages in portage that would benefit from it already, so anything that can be done to help would be appreciated. Thanks...
this problem is actually a dependancy issue on the ebuilds themselves, the maintainer is aware and a fix should follow as appropriate.