No, the caching is done by the OS in the file system cache for non ngen'd
images or on XP and higher in the prefetch (disk) cache for native images
(as the ngen'd images).
A non Ngen'd image (just a regular file) is loaded by the OS using normal
file IO, that means that the assembly passes the cache where it stays until
it's removed in favor of other files. When you load a program a second time
(after the first one has gone) and the file data is still in cache, it will
get loaded from the cache, that's why it loads so fast the second time.
An Ngen'd image is loaded differently, here the OS loader loads the code
image in memory (actually it maps the data into the process space) bypassing
the FS cache completely.
However on XP and higher, the OS keeps part of the loaded native image in
the prefetch directory (under \windows) , which it loads as part of the boot
process. That means that programs that have been loaded recently (the
threshold is a couple of days depending on the size and number of images
loaded) are partly preloaded to speed-up the final load process.

Willy.

Just the method.

You'll see that on plenty of applications. All it means is that the
binaries and libraries required by the app are then in the file system
cache, so don't need to be loaded from the disk.