This is a modified version of the default task list plasmoid from KDE 4.3 beta. It has a new configuration option "Show vertically" and shows tasks 90 degree rotated when in a vertical panel. This way it fits as much text as in a horizontal panel. In horizontal panels it is displayed normally. Tasks are rotated -90 degrees in panels on the left and 90 degrees in panels on the right (see screenshots). Grouped tasks are also rotated.
Hope you like it. Comments are appreciated :-)
I didn't change much in the default tasks plasmoid, just added a few lines. Added an offscreen pixmap to draw the tasks normally and then draw them 90 degree rotated to screen. And I swapped the width/height of the preferred size of the tasks.