Flash 8.5, ActionScript 3.0
Just went to a talk at Max by Gary Grossman about Flash Player 8.5 (not released yet) and the changes they're making.
ActionScript is becoming a (more) strongly typed language. You'll be able to declare variables with type, and have the runtime know the type of the object (AS2 let you declare the type, and the compiler would use it for type checking where it could, but the runtime didn't care).
Binary socket support. Byte array support. Combine these two and you can use Flash to write a client for just about any protocol.
But the exciting change is that ActionScript is becoming a JITted language. This means your code will be compiled to native assembly code before being run, giving a huge boost in performance. They're talking about improvement of about 10x.
Add this to the stuff Flash already has going for it and it becomes a much stronger environment for rich internet applications.
There's also Flex Builder 2, which is an Eclipse-based IDE you can use to write Flash applications.
You can download some of this stuff now from Macromedia Labs.