That's a good question, and we've got some ideas on dealing with abuse.
One option is to implement a moderation system, where a group of moderators have the ability to delete/remove untoward postings. Or we could take a more stringent approach and require someone to have their posting approved by a moderator before it actually appears. Anyway, it would work in a very similar fashion to how moderation works on a Network54 forum. We can even take that a step further and have group moderators based on location - i.e. if you were in a "Los Angeles Moderators Group" you could only edit/remove/approve posts that appear in the LA area.
Another option is a scoring system, where all registered users can score posts, and based on the score a posting may or may not appear (or may only appear if someone actually wants to see a post with a negative score). It would also be very similar to the Network54 scoring system we have in place, except this time when a post reached a certain threshold (i.e. received 10 low scores) it would be removed, or would appear last in the list of results.
Required registration is another option - although it would be nice to keep the system as open as possible. We could do something with the scoring system such that a registered user's post would automatically get a default (higher) score.
A combination of these types of systems should work well - we just haven't gotten to that point yet since Wayki is a very new service and is evolving on a week by week basis.