Very nice! Well done.

So resources are now elements...does that make the 'document tree' the 'resource tree' now? What other naming has changed?
Not quite, I think.
In the new terminology, Resources and Elements are two different things.
The stuff in the tree is now resources.
Documents
Weblinks
The things on the tabs are elements
Snippets
Chunks
TVs
Templates
Plugins
This is important in transition to Revolution where they are all in the trees on tabs (or optionally in an accordion menu).
In Revolution, the tree looks like this (for now anyway):
Resources Tab Documents
Weblinks
Symlinks
Static Resources
Elements Tab Snippets
Chunks
TVs
Templates
Plugins
Categories
Files Tab (file tree here)