Flex 2 Macromedia encourages users to “Writing your own AMF/Remoting packet.”
After hearing about the Binary readers and writers I was quite excited. Now look what you can do 
) And finally you have access to a simple StringBuilder looks like c#'s. There is even a Zip compression build in for supporting servers.
"Possible uses of the ByteArray class include the following:
- Creating a custom protocol to connect to a server.
- Writing your own URLEncoder/URLDecoder.
- Writing your own AMF/Remoting packet.
- Optimizing the size of your data by using data types."
Also to note is the inclusion of proper Error reporting in AS3, with stackover flow reporting ) Smiles all round really.
Sad to see they havent fixed the transparency issue in windows applications, Snif snif, pweaseeeeee!!!