The theme system needs to be documented. This already has been started on the theme page.
A guide to document the common administration tasks as installing, upgrading, configuring, etc.
A guide for common user actions as adding albums, items, document each module and feature; what it does, how to use it, etc.
A module howto and an introduction to the G2 framework, how to do common stuff, etc.
Ideally, we'd have a package of all required and optional binaries for the supported platforms. Or link to the available precompiled binaries and offer a package of the missing binaries on our site.
2005/08/08 update: there's now a Installation Requirements page and an improved Installing an Image Processing Library Howto. WHat's missing is: Binaries for ffmpeg on non-windows platforms, for imagemagick for linux, for zip, unzip, jhead and php-cgi.
A huge FAQ and a specialized knowledge base can simplify the everyday work as a support staff member tremendously. e.g. that blank site admin -> module pages could be caused by a too small memory limit (16mb is sometimes not enough), or how to deal with data corruptions, etc.
Don't ship the final release with all available languages, only with en_US. But users that can't extract a language archive over an existing G2 install will have a hard time adding the translation files in all modules manually via FTP.
The edit permissions UI was discussed again and again and the only conclusion was that it needs to be reworked. See [this forum thread] for a discussion of where this might lead.
See sf.net task 111196.
Create a codex page for modifications and customizations such that user can create their own Howto's, modifications, links to modules etc. and add them to this page.
Don't forget to copy / import the User Contributions page from the gmc wiki(done by valiant).
What's still missing is: instructions on how to contribute / how to create your own wiki page / add a link to your contribution to the contributions page. Maybe better organize the user contributions, create a single entry page and a page for each category (modules, themes, ..).
See sf.net bug 1255320 (fixed by valiant)
Currently, we ask for at a memory limit of at least 16mb, else we show a warning in the installer. But even 16mb seem to be not enough for simple tasks like displaying the list of modules (site admin -> modules). 12mb seem to be not enough to delete an album. (in some cases). Most often, the user just sees an empty page or something like that. We should track down the memory consumption, e.g. if it is the translation files or what else.