1) installs 3rd party plugins.
2) factory restore or ssh in and manually remove them
3) factory restore

ssh in and manually remove what you don't want.

Thanks for the reply. So the patchstick will only *add* some 3rd party plugins? 
It doesn't otherwise create 
partitions or rearrange any of the ATV's original files or structure? So, I 
won't lose any content of my own that 
is currently stored on the ATV's hard disk? Also, as I understand it, the 
factory restore will do just that: restore 
it to the factory condition, which will not contain any of *my* content. So, 
the way to restore the ATV to the 
*pre-patched* state (not the factory default) is to determine what plug-ins the 
patchstick installed and then 
manually remove them with ssh? Ssh is not installed by default, though, is it? 
So, how do I remove *that*? It 
doesn't appear that I can remove ssh *using* ssh and in so doing restore my ATV 
to its pre-patched state, 
right?

http://code.google.com/p/atvusb-creator/source/browse/#svn/trunk/atvusb-
creator/payloads/patchstick/packages

This is the source code that installs various packages. By looking at the 
various bash scripts, you can see 
everything that is installed.

If you are nervous about the patching process, I suggest you might pass on this 
project.

I was afraid you would respond this way!
I am not nervous; I just would like to know exactly what's going on with the 
patching process. 

Like I've mentioned, all code is open source, nothing is hidden. With ssh, you 
can manually remove everything 
but ssh. To remove ssh, you would have to hook a boot script before sshd 
starts. Quite frankly, no one has ever 
expressed concern over this and I don't see any point of creating such a script 
as tracking what a user might 
install after the patchstick installs it's bits is impossible.