Thanks @jessegrosjean - impressed how quickly this is coming together. Here are some issues here from testing new features:
"Open in New Window" works for folders but not documents. Not sure if this is intended.
View menu offers option to "Show Library" when it's already visible. Clicking this hides the library.
Added "View By" options to library view context menu
Perhaps move this to the View menu as well? Or somewhere else. It seems too basic a piece of UI to hide in a context menu.
Spacebar in library view to Show info panel for selected item
Cool...but I think command-I should do this, too, since it's pretty standard across Mac apps.