It's often forgotten these days, but at its heart Android is a Linux-based operating system (with a healthy dose of C and Java thrown in). Today that association gets a little closer, as the primary Linux kernel version 3.3 is adding some Android-specific code into the primary development branch. Android is technically a "fork" of Linux, but this brings a little of the work that Google and others have done on the Android Open Source project back into the main Linux project directly.
What does this mean for consumers end-users? Not much, really. If anything it's a formal recognition of Android's contribution to Linux as a whole. It will make it much easier for Google and other developers to port code and features from the primary branch of Linux over to Android, no matter what version they're using or what hardware it's intended for. Easier programming on Linux-based desktop machines could very well be in the cards, but only as a side effect, since most of the actual apps for Android are developed using Java tools.
The 3.3 kernel was announced by geek god Linus Torvalds himself, though he made no mention of the Android code being placed back into the main development branch. One of the biggest features that this addition brings is the ability to boot an Android userspace directly from the standard Linux kernel, rather than using one of Google's customized AOSP versions. If you need to grab the latest 3.3 kernel, head over to the Kernel.org website to download it.