It's an "event based" server written in C, meaning that it uses select or poll or some other 'event based' mechanism to do its work.

Erlang might be an interesting choice for your network service, as it allows you to write this sort of code very naturally. It depends on what you're doing, though... Python has some frameworks that work this way, although none so smoothly as what Erlang gives you. Tcl has also had this capability in its core for years, although, like Python, you have to be careful about writing 'blocking' code, something that you don't have to worry about so much in Erlang.