the multiple lines of buttons works automatically, of course, with no configuration needed. new lines appear as space becomes over used. it works nicer than what we had in kicker, really, and it's all still animated and what not. yummy goodness. you may also notice the "only show tasks on the current desktop" option is back.
i can't take the credit for it, though. Olivier Goffart did the heavy lifting and others did miscellaneous clean up of bugs and coding style issues after him. i'd like to backport these features to the 4.0 branch, but will have to ask the i18n team for string permissions.
i'm sure it's only a matter of time before we end up with task grouping and what not. huzzah.