The term "folder" is not bad, it's quite nice in fact.
I would like to be able to see files and folders as all folded items that can be unfolded - inlined into the context folder - all in a recursive photosynth style.
Imagine also "Oslo" integration where a folder is virtual and links into the Repository to objects and are in effect inlined and viewed as in "Quadrant". The application blends into the shell itself; able to unfold its own chrome as well and inline it into the context folder.
A uniform model-based UX such as "Avalon" will probably provide an even better foundation for this kind of experience, or a more integrated flexible foundation at least.
I think we're very used to fullscreen applications and now one application per monitor. Maybe we should be looking toward a more analog desktop experience.
I would also like the browser itself to move out of the page metaphor. To allow homepages to adapt to large workspaces and present more composite views. To maybe show "tabs" as layered, stacked and displaced sheets with Aero switching between them.
Surface Computing (Microsoft or not) is pointing in this direction, albeit with special hardware with a hefty price tag.
The notion of Plasmid widgets, composite or not, extended to entain a taskbar or not. Well I'm not sure I've gotten the big deal yet.