Free wiki hosts
Wikispaces seems especially nice, at first glance. It has a wonderfully clean interface — easy to understand, easy to use. Of course, it's also pretty early in development so there's not a lot of clutter. And they do an excellent job with the out of the box experience.
Wikispaces is focusing the wiki community. And it really is a community: once you've logged in, you can edit any page on any wiki, whether you created it or not. As they say, "Wikispaces are public, so everyone else will have the ability to help build and edit pages."
Interestingly, their T&Cs insist that everything you submit to one of their wikis is automatically under the CC Share-alike license. So that's going to make it unsuitable for a lot of applications, but it's a noble sentiment. This could mean that they compete more with projects like CivicSpace or Drupal than the other strictly wiki projects.
Schtuff is also fairly well-designed. It seems to be further along than Wikispaces, and is open for any kind of use. They don't mention any sort of business model, so either it's going to be advertising, or they're using this as a starting platform for something else.
Anyway, the more I see of this trend, the more I am convinced that productized, downloadable server software is the most-likely-to-succeed business model for a wiki vendor. I still think that the hosted service is a necessary component of the business plan, but it is best viewed as a loss-leader used to get people to in front of the product.
Hosted versions were probably a good place to start for all of these companies. It’s definitely easier to develop and maintain that kind of software with limited resources. You can move faster because you don’t have to worry about an installed base. But there will come a time when making a user-installable version becomes unavoidable. Developers who have been planning for that day will be sailing. Those that haven’t will be facing down months of clean-up and hardening and ease-of-use work which will suck time and stall feature development. I’ve been in that situation before and it’s not pretty.*
All of the products in this market, commercial and non-commercial, are advancing extremely rapidly. At this point, it’s difficult to see why I would choose one of the paid wiki hosts over the free ones. (JotSpot is a slightly different matter: they’ve been able to differentiate their offerings with pluggable applications. If you need those features, there is nowhere else to go at the moment.)
* I know this “plan-ahead” warning sounds counter-XP, but it need not be viewed that way. In XP, you’re supposed to build the Simplest Thing That Could Possibly Work. Well, when you’re developer AND the admin, then the simplest thing is a much lower bar than when someone else has to admin your software. So it’s not that you’re doing more Big Design Up Front, it’s that you have to have an accurate understanding of what the simplest thing really is.