Scheduled actors, both context-switching and event-based, shall not use blocking systems calls such as read/write/select. Thus, actors are of very limited use if it comes to IO, since only thread-mapped actors can do IO without starving others. We therefore need a message-based (?) asynchronous IO layer for actors.
I actually was about to write an event-based actor which performs read/write/select to communicate over a custom transport protocol. So I'd be curious to see how you would wrap these low-level functionality. I've been using Boost Asio for a while, which may be a good source for inspiration when it comes to asynchronous design.
This feature has been implemented in 0.8 as broker actors.