Version: (using KDE KDE 3.5.3) Rename playlist is [F2]. When at the left there is playlist pane, and on the right there is playlist content pane, click on playlist and press F2 -- instead of playlist track is about to being renamed. V.1.4.1.
Unfortunately, your report is not specific enough. But Amarok 1.4.x is no longer actively maintained as all the focus is on Amarok 2.0. Feel free to report any bug you should come across in Amarok 2.0