In Dolphin and Windows Vista/7 Explorer they can list folders laying in the same directory by pressing ">" (in Dolphin) or "▸" (in Explorer) sign what placed right of the breadcrumb. I don't remember the behaviour, but suppose they try too keep the same path if all directories are available (Fast way to switch between folders /home/user/Tmp/dir1/yesterday/12/done, /home/user/Tmp/dir2/yesterday/12/done, /home/user/Tmp/dir3/yesterday/12/done, /home/user/Tmp/dir4/yesterday/12/done, etc by doing only 2 clicks) and reduce the path if there are no dirs, but keep the maximal match (eg if we are in /home/user/Tmp/dir1/yesterday/12/done, but only /home/user/Tmp/dir2/yesterday/12 is available, we will enter in the latter one, not in just /home/uset/Tmp/dir2).

But I don't like these signs though, the breadcrumb bar looks overcomplicated with them and they are too small to use them with comfort. My suggestion is to use Google Chrome web browser approach: they don't have any dropdown history sign, but user can list its history by holding left mouse button over the "back" or "forward" buttons. I think this idea can be used to list these folders without using these ugly signs to repeat the similar functionality.