iPod Games Dissected

iPod games purchased from the iTunes Stores are located in Music->iTunes->iPod games. They come as normal folder with a .ipg extension.
Once purchase, using StuffIt, one can unzip the folder and get a Tetris 1.0.ipg Folder for example (do not forget to make a back up copy before).
In the folder, there are different files: audio in .wav (sound effects), a file Mu.m4a (music). So one can recover them, and use them for other purpose, or do the opposite ;)
One will also find .pix files (probably corresponding to texture or graphical elements of the game)
There are 4 executable files: iTunesArtwork, iTunesMetaData, Strings.dta and tetris.raw.lcd5, and 2 .plist files.
To conclude, there are 2 additional folders: "Executables" (containing probably the graphical engine) and "Resource" corresponding to the geolocalizing information (.fr for France) including a Description.xml file and a .jpg file corresponding to the game user manual and description found in iPo games library.
To my point of view, some files can be modified without much problems, and I expect some "HomeBrew" games to appear for the iPod in a couple of weeks, as it already happens with the PSP and the Nintendo DS. Except if Apple has locked the system by using certificates or DRM inside iTunes.