Yahoo just announced that it will support OpenID.
OpenID is an interesting initiative to provide single-sign-on to user. It is both secure and simple, so it will be probably spread out quickly.
You can get your own OpenID by suscribing to a provider or setting up your own server if you got a domain name.
I will soon write an complete post about it, but now you can already check the official OpenID site.
Note that this blog already supports OpenID !