Google’s universal sign-in system, Friend Connect, which just opened to all Websites two weeks ago, now accepts Twitter IDs as a sign-in option. That means when you visit a participating Website that accepts Friend Connect as a log-in option, you can sign in using your Twitter account. If any of the people you follow on Twitter are also members of the third-party site, they will automatically be added as your friends.
Friend Connect also supports IDs from Google, Yahoo, AIM, and OpenID. For instance, I tried this on the Go2Web2.0 blog, which has implemented Friend Connect, and it gave me the option to use my Gmail or Twitter accounts (I could also use Orkut or Plaxo). I used my Twitter sign-in without a hitch. (Update: Actually, this is a little confusing, but it signs you in first using one of the four credentials above and then asks you if you want to add Twitter).
The race is on between Friend Connect, Facebook Connect, and MySpaceID to sign up the most third party sites. Adding Twitter as an issuing party is a big win for Friend Connect because sites are going to choose the sign-in system that gives their visitors the most options and broadest reach.
There is nothing stopping sites from implementing more than one sign-in system, but at some point presenting visitors with too many options becomes confusing. For instance, we use Facebook Connect, in addition to our own sign-in system. Should we add Friend Connect? Probably. MySpaceID?
It’s only been a couple weeks since these have become widely available, and already universal sign-in is anything but. Here is a list of sites that are live with Facebook Connect, and some example Friend Connect sites can be found here (if anyone has a more comprehensive list of sites live with Friend Connect, please add to comments).