Tested with another users, and the same problem, but after upgrading KDE to 4.8.3 and Clementine to the dev branch, media keys work again. So in this case, it was a problem in an official package.
Tested with another users, and the same problem, but after upgrading KDE to 4.8.3 and Clementine to the dev branch, media keys work again. So in this case, it was a problem in an official package.