Notify-OSD (https://wiki.ubuntu.com/NotifyOSD) is a nice new feature of the up-coming Ubuntu 9.04.
Launchpad site: https://launchpad.net/notify-osd
Installation instruction for Ubuntu 8.10. Both are okay for me under Ubuntu 8.10.
1. From Alex Rybicki:
2. From Softpedia:
I also tried it under Fedora 10 (Gnome and KDE) and it seems to work there as well. There is a bug report for Fedora and hopefully it will get solved soon.
I think ease of use is an important feature if Linux wants to get the heart of more users. Features like this are really good to see in Linux distros.