What other alternatives are there? (Twisted, EventMachine, ...?)
Lots, depending on what you're doing: scala actors, akka, STM in haskell and clojure, GHC (lightweight) thread manager, F# async's and MailboxProcessor; apple GCD; Microsoft Message Queuing (MSMQ),Completion Ports. ZeroMQ, rabbitMQ/AMQP
(but you should spend some time looking at erlang)
Lots, depending on what you're doing: scala actors, akka, STM in haskell and clojure, GHC (lightweight) thread manager, F# async's and MailboxProcessor; apple GCD; Microsoft Message Queuing (MSMQ),Completion Ports. ZeroMQ, rabbitMQ/AMQP
(but you should spend some time looking at erlang)