Finally the OAuth Core Specification 1.0 was released. For those who don't know, OAuth allows the you the User to grant access to your private resources on one site (which is called the Service Provider), to another site (called Consumer, not to be confused with you, the User). While OpenID is all about using a single identity to sign into many sites, OAuth is about giving access to your stuff without sharing your identity at all (or its secret parts).
We'll have to read the specification in detail, and see if the big players implement their service providers. Since OpenID 2.0's draft is about to be approved (and since both Google and Microsoft have new OpenID support), it will be interesting to see how both OpenID and OAuth complement each other.