Sticky speaking it is legal. However, participating, using or involving yourself with homebrewed software is, like most free/indie software, at your own risk; Nintendo (the corporation) doesn't support it.
Now, involving ourselves with a homebrew community has risks and benifits, that, like above, aren't easily categorized:
#1) It's an active community (See
Recent Changes and
Statistics); if we could get some of that here, it would be to our benefit
#2) The members of the wiki probably have knowledge on how Wii hardware and software works, which would help NintendoWiki.
#3) Simialry to Pikmin Fanon, they are almost entirely Fan-based content. But unlike Fanon, there's some risk that would be carried with it.
I mean, we could be a good testing ground for their software, being we are all fans of Nintendo, and most of us probably have a Wii. But we may then need to issue a disclaimer saying NIWA takes no responsibility for Voiding of Warranties, damaging of systems, etc. Anybody who chooses to be a software tester would take full responsibility over the use of the unauthorized software.
So, i think we should bring them in, but only if we take the proper precautions to protect ourselves, if anything were to come up.