While we are always getting excited for the next Linux 2.6 kernel release (heck, we are barely halfway through the Linux 2.6.36
kernel development and we are already getting excited for Linux 2.6.37
with its driver improvements
), but sometimes it can be easy to forget that there is still a maintained Linux 2.4 kernel. The Linux 2.6 kernel has been around for nearly seven years and is used by all new Linux distribution updates, but there's lots of enterprise and embedded devices running off this old kernel. The Linux 2.4 kernel though may have just reached an end-of-life state with the just-released Linux 18.104.22.168 kernel.
Willy Tarreau has been the Linux 2.4 kernel maintainer for these infrequent 2.4 kernel updates that largely incorporate bug-fixes and few back-ports, but even he is switching over more of his Linux 2.4 installations to using a long-term-supported Linux 2.6 kernel to the point that he has few 2.4 systems left. As part of his Linux 22.214.171.124 announcement, he has proposed his 2.4 end-of-life plans.
If no critical issues are discovered in the Linux 126.96.36.199 kernel within one year (until September 2011), there will not be a 188.8.131.52 kernel release or any future 2.4 revision. Willy is still accepting 2.4 patches, but unless some critical issue is discovered or other change that would warrant a new kernel update, there is just a year left to switch over to the Linux 2.6 kernel before the 2.4 support goes away for good.
The Linux 2.4 EOL plans are shared in this kernel mailing list message