Here's my attempt at contributing to the FAQ, you can copy it up to the top post if you want. I'm no expert, and this is just what I've pieced together myself, so if I'm wrong on anything, someone please correct me.
I want to know more about how all this works!
Android is software that run on top of a custom build of Linux. XDAndroid is the project that is porting Android to our HTC phones. There's a lot of moving parts, and each of them is updated separately. Here is a summary of what's going on:
initrd.gz is a tiny disk image used to boot a Linux kernel, before the real file system can be mounted. The build of this used for XDAndroid is stable, and updates are rare.
zimage and
modules together are the Linux kernel, and form the core operating system. This is where hardware drivers are included.
http://gitorious.org/linux-on-qualcomm-s-msm/linux-msm is a list of the changes that have been added lately to the kernel
http://irclog.netripper.com/?chan=htc-linux is a log of the kernel development IRC channel if you want to see what the devs are working on these days
rootfs.img contains additional files needed to run the basic Linux system.
http://xdandroid.southcape.org/rootfs/ is a list of the changes that have been added lately
system.ex2 contains Android's extra parts that run on top of Linux.
http://xdandroid.com/irclogs/ is a log of the XDAndroid development IRC channel
http://forum.xda-developers.com/showthread.php?t=711692 the XDA thread usually has a summary of recent changes
Where can I go to find the latest versions of each of the parts?
http://xdandroid.com/wiki/Main_Page