The shortcut is `-`
Try `cd -`
If you want to use this in your prompt, you have to refer to it with `~-`.
See the example:
[echox@kaffeesatz ~]$ cd /tmp
[echox@kaffeesatz tmp]$ ls
cron.iddS32 serverauth.CfIgeXuvka
[echox@kaffeesatz tmp]$ cd -
/home/echox
[echox@kaffeesatz ~]$ ls ~-
cron.iddS32 serverauth.CfIgeXuvka