A long wanted feature in gnome is flashing taskbars, to use with programs such as GAIM for new IM notification and others. The code has been submitted in a gnome bugzilla and was submitted into the gnome cvs so I patched the current version of libwnck to handle the flashing taskbar.
To get the patched version of libwnck:
wget http://z.narutochaos.com/ubuntu/libwnck ... 1_i386.deb
This downloads the patched libwnck.
sudo dpkg -i libwnck16_2.10.0-0ubuntu1_i386.deb
This installs the patched version.
sudo echo libwnck16 hold | sudo dpkg --set-selections
The command keeps apt-get from overwriting it.
This command closes the gnome panels and they automatically restart.
After this, your taskbar should flash when the window manager is sent the urgent hint.
To get GAIM to use flashing taskbar notification:
Start up GAIM and click Tools and then Preferences. Then click on the "Plugins" preference and check the checkbox beside the Message Notification plugin. After that there should be a Message Notification preference entry under the parent "Plugins". Click on that and it should give a list of options for the Message Notification plugin. Check the box for "set window manager "URGENT" hint and configure the rest of the options to your liking. Now, when you recieve a new message, your taskbar will flash to notify you.