I installed today the latest Calibre on my brand new Jaunty (two days old).
It's working, but on install, I read this "threatening" remark on the terminal screen
quote
Installing MAN page for calibre-smtp
Trying to setup udev rules...
* Restarting Hardware abstraction layer hald [ OK ]
udevadm control expects commands without underscore, this will stop working in a future release
Setting up bash completion... done
roger@roger-laptop:~$
quote
What exactly will stop working in a future release ?