Fedora uses Plymouth to provide a flicker free boot for quiet some time now. Debian has packages in experimental but it took some patches to get these working. After adding a Debian logo the boot splash actually looks quiet nice. The initramfs and init scripts do need some more work but it's basically working. Thanks a lot Daniel for merging these so quickly!
To enable Plymouth you first need to set up KMS in the initramfs. For an intel based card you can do this by either adding
to /etc/initramfs-tools/modules or by setting
on the kernel command line. Then install plymouth, set a default theme and update the initramfs:
aptitude install plymouth plymouth-plugins-all plymouth-set-default-theme solar update-initramfs -u
Finally add splash to the kernel's command line (e.g. by adding it to /etc/default/grub).
Afterwards reboot and you should see the solar flares:
We're still not fully there yet since we need a newer gdm for a flicker free handover. Fortunately the Debian GNOME maintainers have already prepared a new package in svn. We also need proper support for encrypted disks, asking for the passphrase works with this fix but cryptsetup needs support for it.