Change Plymouth Theme

In Ubuntu 10.04 LTS (Lucid Lynx) uses 'Plymouth' for its boot splash.

Installing a Plymouth Theme

sudo update-alternatives --install /lib/plymouth/themes/default.plymouth default.plymouth /lib/plymouth/themes/simple/simple.plymouth 100

Set the New Theme as Default

sudo update-alternatives --config default.plymouth

Update the Boot Image

sudo update-initramfs -u

NOTE for LTSP

You need to follow these steps from within the chroot.
Once the update-initramfs -u command is done, you need to exit the chroot and copy the new image (/opt/ltsp/i386/boot/initrd.img-2.6.32-22-generic) to the /tftpboot/ltsp/<ARCHITECTURE> directory so that it can be picked up by the clients.