Just a quick roundup of OpenID, which I’m sure will have wide-spread acceptance and usage in the user management space for both web-based as well as software applications.
OpenID is a decentralized system to verify one’s online identity. On OpenID-enabled sites, Internet users do not need to register and manage a new account before being granted access. Instead, they only need to be previously registered on a website with an OpenID “identity provider”, sometimes called an i-broker (like MyOpenID and many more). They can also link to this identity provider from another website they own and log in using that website’s URI instead, allowing them to connect their identity to their website. A website which accepts sign-ins from OpenID is called a “relying party.”
OpenID is increasingly gaining adoption amongst large sites, with organizations like AOL both acting as a provider as well as Wikipedia announcing that they will support OpenID. In addition, integrated OpenID support has been made a mandatory priority in Firefox 3 and Microsoft is working on implementing OpenID 2.0 in Windows Vista.
More about OpenID at Wikipedia.