Six Apart’s TypeKey is a damn fine authentication system, and its open API means it can be implemented in any application, not just in Movable Type. A common complaint about TK is that it runs as a centralized system on Six Apart servers. If Six Apart tanks or goes down for a while, your authentication system goes with it. LiveJournal’s Brad Fitzpatrick has launched OpenID, an open and distributed authentication system with similar goals, but without the problems of centralization.
But there’s no denying that despite its efficacy at stopping spam and limiting the strain on server resources, required authentication on comments inhibits free-wheeling conversation and casual commenting. To overcome this obstacle, an authentication system needs critical mass, needs not to be regarded as alien or invasive to the user’s privacy. If OpenID can solve the social barrier problem and gain mass acceptance, it could have legs.
But wait… Six Apart now owns LiveJournal, and OpenID will compete with TypeKey. The page says that Fitzpatrick is working to make TypeKey into an OpenID server. Making that so could amount to an implied admission by Six Apart that centralization of an authentication service by a commercial entity puts a lot of people off. This could be interesting to watch. Discussion on Slashdot.