No. 1 - Keep Information Relevant
Having a Wiki seems tempting, but it is important to keep it's information related to GP2X development. This Wiki isn't Wikipedia. A good example of how to do it right is the latest revision of the Linux article.
No. 2 - Respect Copyrights
Do not use copyrighted materials like pictures, music or other media (including text) in the Wiki without permission. This Wiki is only meant for freely available information about GP2X development. If you need pictures of the GP2X or diagrams, it is important that you have the rights to use them, or make them yourself. Do not use an image if you are in doubt about it's status.
This rule is to avoid any legal implications.