I think it depends on a number of things, among them being:<p>• is your target audience geeky? (that is, will the people coming to your site already know what OpenID is, or will you have to educate them on it?)<p>• how in-demand do you anticipate your service being? (that is, do you think it'll be <i>so</i> compelling that people will overcome the hurdle of having to sign up for an OpenID / figure out which of their OpenID providers to use?)<p>• are there other services in the same vein that use OpenID? (that is, is there precedent?)<p>• is there an alternate form of ID (Twitter? Facebook?) that would make more sense for your anticipated userbase?