You can clone with
It appears from a brief skim of this that it is intended to help detect when source files have been updated since the last time the file was loaded into the running JVM. Are you thinking that we would add this feature to clj-ns-browser?
If you were hoping that it would help detect changes to a namespace's contents, i.e. which symbols were defined, or tracking when their definitions have changed, I suspect that the polling method used now is as good a method as any.