Group members: 2866
Elgg's documentation is available at this wiki: http://docs.elgg.org/. There is also an API reference generated from the code at http://reference.elgg.org/. Also, if you are serious about developing with Elgg, be sure to join the Elgg developers google group: http://groups.google.com/group/elgg-development
If you are looking for help on theming Elgg, be sure to join to the Theme development group.