With the recent outburst of PSGroove release from mathieulh, you may not need this, but with the pictures that are shown below are what looks like a indeed fully working diagram of either the original PSJailbreak USB dongle itself, or maybe one of the soon to be released clones such as x3Jailbreak and PS3Stinger, to some people it may looks like the x3jailbreak USB dongle device.
The schematics above use the smaller version of Atmega16 chip, compared to the bigger Atmega chip version used by PSGroove, which is the Atmega32. Nevertheless, after looking at the code it should be possible to put in the smaller version.
Well, after you merge these two releases and you can create your own professional PSJailBreak clone in just a matter of few days, and you probably want to think a name for your clone (Sorry, x3JailBreak is already taken!), and then build a website showing your crappy Youtube video of the dongle and take the pre-orders!
Special thanks to garyopa and ModRobert for pointing this news out.