You have probably noticed one of the changes in Windows Vista Explorer: they removed the Upper Folder button.
Probably, Redmond guys thought it was enough with the newer folder navigation bar (like this one ), what is true most of the times, as it allows to one-click navigate not only to the upper folder, but also several levels up.
The CON comes when you navigate into a folder with a long name. In that case, the explorer won´t have room for any other folder than the current, showing something like this:
When that happens, you will have to click in the << symbol to pop the folders context menu up, and select the desired folder, what means two infinitely long clicks (they should have keeped the parent folder in every case, with some ellipsis (…) if the name doesn´t fit…).
A very easy way to override this is to use the keyboard shortcut that takes you to the upper folder: ALT + UP ARROW
And that´s it!