My 6 y/o just got a Leap Frog DiJi from Santa-son
Turns out it is Linux based under the hood.
The hardware...
    * 320*240 TFT LCD.
    * 393MHz ARM 926 CPU.
    * Partial OpenGL ES 1.1 support
    * Familiar DPad and button layout.
    * 2 Gigabit NAND (so 256 MegaBytes).
    * 32MB DDR Memory.
    * Custom cartridge for additional storage (no SD)
http://www.leapfrog.com/en/home/support/product_pages/didj.html

I was looking around for some GPL information at the LeapFrog site and could find none, but some folks have started hacking it already...

http://andrey.thedotcommune.com/2008/11/didj-hacking.html

http://blogs.distant-earth.com/wp/?p=64

Santa left the Star Wars version which was $30. (I think) at the PX w/ 1 cartridge.
The other version is $49.
Looks like a great old school emulator platform.
BB

After the post I found this...

http://www.leapfrog.com/etc/medialib/leapfrog/legal.Par.14642.File.dat/Additional%20Third%20Party%20Notices%20for%20LF%20Connect%20Application%20.pdf

A proper GPL notification!

Billy,

http://medialib.leapfrog.com/didj_opensource_code/Didj-Linux-3197-20080429-1631.tar.gz

  Here's the link to the Tarball for the Kernel, source and libraries released by Leapfrog for this device... looks like people are trying to get things to work... haven't find a complete solution yet... 

This device looks like it selling cheap..some places for about $20 now....

Okivash

Noticed that recently back in the states.
I am afraid it will not be around in this form much longer.
It is just not taking off as a learning tool.
Both of my boys love to play it.
The byproduct of them actually learning something is nice.
The software is selling for about $11 at FRY in Seattle.   
But there are not many games available. 
Hardware hackers may have a good time with this device.