I will have to use the runEventLoop(), a server will push information to a client from time to time.
If you say there are vibe-specific mutex and signal, then I can try to come up with some solution
using these two. I will probably don't have a time until tomorrow, but I will try to report my
progress for anyone interested. If you have any ideas that might help, feel free to throw them at me
;-)

Just for the record, I would also like to have something like std.concurrency available in vibe.d
and probably will do an implementation with a compatible API at some point. The arguably better
alternative would be to extend std.concurrency so that it is able to use fibers and custom
synchronization primitives. But since that will probably not happen anytime soon (or at all), my
plan is to go with the former solution, although it kind of hurts to duplicate Phobos functionality.