Some background, but probably way too much information:
I'm porting a security framework/platform, Apache Shiro, written in java, to python. Their next major release, 2.0, re-factored quite a lot of source. Part of the re-factoring includes migration of a template design pattern to something that is eventbus based. Rather than use Apache Shiro's eventbus design, though, I intend to use pypubsub. You've already put pypubsub through several iterations of feedback and I hope to benefit by that. Shiro supports multithreaded processing, and its eventbus (in earn alpha dev) seems to be reflecting that through locking access to shared collections. So, this has lead me to my inquiry about whether pypubsub could provide something as good, if not better, than what the shiro team has with their homebrew eventbus.