While Plymouth is now quite mature
and didn't see too much new activity in 2011, it may be finding its way into another Linux distribution. The openSUSE developers are debating to use Plymouth as a replacement to bootsplash.
Since late December there has been a discussion on opensuse-factory
about switching over to Plymouth as the boot splash screen as a replacement for bootsplash.
Not everyone though is happy with this possible move, with some still believing Plymouth is of "alpha" quality while others not liking it since its hard requirement on KMS (kernel mode-setting) for an ideal experience. With a KMS-supported driver and hardware, Plymouth is able to deliver a "flicker-free boot experience", which is one of the project's main selling points. If you're using the NVIDIA binary driver or any other non-KMS graphics driver, you get dropped back to a reduced graphical / text mode.
The discussion concerning Plymouth for openSUSE is still ongoing with no decisions having been made yet.
Plymouth began as a Red Hat project back in 2008 as a RHGB replacement
where it first found its way into Fedora. Since then it's been picked-up as the boot splash screen in Ubuntu, Mageia / Mandriva, and others.