[Edit May 21, 2008. Read on if you like, but you can now download the docs directly. https://theflashblog.com/?p=387]
There have been a few links around about how to compile for the Flash 10 player. But there is no public online reference that I know of that lists out the new objects, methods, etc.
I’m not at liberty to publish anything myself, but you can do some introspection to find out some more about them yourself. Compile a SWF targeting Flash 10 and use describeType on the object you want to know more about:
[as]describeType(DisplayObject);
describeType(Event);
describeType(Sound);[/as]
You’ll at least have access to the new properties, methods, params and types.