Adam - I agree their is value to be had from a wiki beyond the scope of the current docs.
soundcyst - I agree with you 100%, except :-)
1. some documentation pages may be autogenerated from e.g. code, and it migt be a PITA to try to incorporate user content. I'd prefer not to create extra work for LeafLabs. If they decide it's no problem, strike this,
2. Having revision control doesn't remove the need to check for accuaracy, and that is work. I'd prefer not to create extra work for LeafLabs. If they decide it's no problem, strike this too,
3. there may be liability issues which LeafLabs have to take responsibiity for. A customer who says "I bought this because the documentation said ...", has rights in Europe which can not be answered with a "oh, yes, someone changed that page, and you bought before we had got to correct it", and
4. LeafLabs staff may want some time to get accustomed to the changes, and see how it works out. LeafLabs may want the ability to 'protect' pages.
I am not an expert, but the monome.org stuff I've seen says it is exclusively for non-commercial use. That restriction may remove some of the issues, and so LeafLabs and monome may not be an "apples for apples" comparison.