Here are some notes about the experience using the Sony Playstation Portable with Quake and/or Kurok.
and point out differences and making notes:

The PSP
The PSP needs hacked to run Quake. Generally you buy a Pandora battery and it comes with instructions on how to do this. That isn't so hard. I bought mine from here for $24 +/- ( http://www.pandorasales.com/ )
The PSP has a small "memory stick" and with a USB to 5-pin cable plugged into the PSP, you can use it like a USB thumb drive.

To run Quake or Kurok, you access the memory stick in the menu under Games and select the game and press "X".
Note: Whatever command line you want to use is controlled by a cmdline file.
Input
The Sony PSP runs Quake very well. It's like a mini-laptop. Since I'm also writing this for the benefit of people who don't have one.
Features:
1. No keyboard obviously
2. No mouse
3. Analog joystick built-in, effectively works as a substitute for the mouse.
4. Four directional buttons.
5. "Left" and a "Right" button at the top that you can't really see in a picture (sort of a Nintendo GameCube controller L and R buttons).
5. A set of 4 buttons: triangle, square, circle and cross ("X"). The Cross button is essentially Enter. The circle button is essentially escape. The Triangle button is often used for options.
6. Sound +/- buttons, start and select. And a couple of other ones.
Using the analog stick and whatever 4 directional buttons you choose to use for control, playing Quake on the PSP isn't bad at all. You won't be able to take on in nightmare difficulty settings but fighting the monsters on easy is fine. Navigation is sub-mouse ease of use, but due to the analog stick, you can get around quite well.
Experience
Console. The Sony PSP has no keyboard but Kurok has a popup keyboard. It works, is functional but is not convenient but far better than no ability to type letters at all. Every PSP engine desperately needs a command history like JoeQuake (and Qrack and ezQuake).
Network. I connected Kurok to my PSP and vice-versa. Works both as client and as server. No current PSP engine is NAT fixed. The PSP has wireless and only wireless; wireless uses routers; routers use NAT. Ugh! (). Desperately needs a server browser for sure (a is a good start, but that'll suck quick enough.) Fortunately, there is libcurl for the PSP so a type server browser should be within reach.

(But unlike DarkPlaces and Quakeworld's true serverbrowser via heartbeat, the ProQuake 4.10 draws from a URL and actually requires infrastructure-- aka it pulls from the QuakeOne.com server feed developed by ).
Music. Kurok has MP3 support via hardware.
Network Notes. The Sony PSP can either connect PSP to PSP or via a wireless access point (your router) via "Infrastructure". Kurok has a nice little built in thing to active this.
Graphics
It looks like GLQuake and you wouldn't be able to tell the difference. Except the resolution is going to be 480x272.
The Differences From a Code Standpoint
Different floating point math functions, uses PSPGU instead of OpenGL, you have about 20 MB to play with on the PSP 1000 series since it has 32 MB but about 12 MB is overhead. The 2000 series "Slim" has 64 MB total so maybe about 40-50 MB.
Texture memory is a concern. I noticed in Kurok it deletes unused textures on each new level. Not surprising.
Input controls obviously. The network code is Linux-like/OS X-like in the non-operating system specific parts, obviously.
Other than that, is for me (as someone who likes Windows the best for coding due to and hating OS X cursor keys) is easier with the PSP in Cygwin than anything short of MSVC6.
No doubt some PSP by-products will be forthcoming soon. Plus I'm going to help the make their engine available in the same or similar form on Windows [Mac OS X version will probably automatically happen too] and I intend to hit ProQuake then Kurok and then Solitude to do this in the best manner.