I post this question since new nautilus is very 'keyboard unfriendly', specially for one-key shortcuts. From 3.4 to 3.6 the very useful 'backspace' shortcut to go to parent directory has gone (along many other features).
In particular I would like to know how to go to the parent directory.
It's not obvious looking at the user interface that there are any shortcuts. However most of the ones that worked in Nautilus 3.4.2 (as used in 12.04) still work in 3.6.
This list may not be exhaustive, feel free to edit this answer to add more if I have missed any out. All the following work in Nautilus 3.6 (as shipped with Ubuntu 13.04):
New tab Ctrl+T
New window Ctrl+N
New folder Shift+Ctrl+N
Open folder in new tab Shift+Return
Properties Alt+Return
Close window Ctrl+W
Close all windows (quit) Ctrl+Q
Make link Ctrl+M
Add bookmark Ctrl+D
Edit bookmarks Ctrl+B
Undo Ctrl+Z
Redo Ctrl+Y
Cut Ctrl+X
Copy Ctrl+C
Paste Ctrl+V
Select all Ctrl+A
Select items matching Ctrl+S
Invert selection Shift+Ctrl+I
Show hidden files Ctrl+H
Zoom in Ctrl++
Zoom out Ctrl+-
Normal size Ctrl+0
List view Ctrl+1
Icons view Ctrl+2
Go to home directory Alt+Home
Go to parent directory Alt+Up Arrow
Go back Alt+Left Arrow
Go forward Alt+Right Arrow
Go to specified location Ctrl+L
Search files (find) Ctrl+F
Rename F2
