SWX RPC is a remote procedure call protocol encoded in SWX. It’s simple enough that you can get up and running with it in about five minutes. SWX RPC is perfect for building mashups (with easy-to-use APIs for Flickr, Twitter, and others), mobile applications (Flash Lite 2.0 and 2.1), and other data-driven Flash sites and applications.

AS3 version will be available early next year.

More info at SWX.