Well the img files are basically like iso files for cd's. It is basically the "disc" copied bit by bit into a file. Under linux you can mount such file systems as if they were the actual "disc", and then browse through them just as you would a cd, usb drive, or hard drive. So upon mounting the img files I was able to browse through what windows users can equate to as the tv's "c:" drive. Basically all the linux config files are there along with the standard executables and what I would assume are the binary drivers for several of the tv's systems(display, sound, i/o). One of the files(exe.img) contains what appears to possibly be the main program for the tv....not sure though.
This stuff is mainly of use to someone with the time to reverse engineer the various drivers and compare them to the 89 series. Hardware comparison would also be important. Once you know how everything works it is easy enough to change as you see fit. Since it is linux you could even make your own programs to run on it rather easily. It is running MontaVista Linux pro 3.1, kernel 2.4.20, they appear to make linux distros for various embedded applications including set top boxes.
Custom firmware is always fun, I have an older htc pocketpc phone that people reverse engineered and made a tool where you can customize the firmware through their web site, download the firmware image it produced, and burn it to the phone....very cool.
I can talk geek all night....but i will save you all from that.