It looks like we just announced that we'll be supporting OpenID at the RSA conference. Official details are in the press release Microsoft Outlines Vision to Enable Secure and Easy Anywhere Access for People and Organizations which states
To further enable the vision of secure and easy anywhere access, Microsoft today announced the following product milestones and industry alliances:
On the heels of the Windows® CardSpace™ general availability launch in Windows Vista™, Microsoft demonstrated momentum with industry partners that are working to apply this technology to help consumers realize a more confident online experience. This includes the announcement of collaboration on use of Windows CardSpace with the OpenID 2.0 specification. Through the support of the WS-Trust-based Windows CardSpace experience, consumers can take advantage of increased security against phishing attacks without adding complexity to their identity management experience. Also at the conference, Wachovia Corp., Arcot Systems Inc. and Corillian Corp. showcased a proof of concept demonstration using Windows CardSpace to deliver a simpler and safer online banking experience for customers.
I'm glad to see the Web platform teams at Microsoft getting better at watching what's going in the Web developer community and adapting their plans to accomodate them. AJAX, RSS, and RESTful Web Services are all trends that started outside the B0rg cube that the platform teams have embraced after some initial resistance. With OpenID it didn't take as long for us to go through the NIH<->FUD<->Acceptance<->Approval<->Adoption cycle that I've come to expect from my fellow B0rg. It seems we have adapted.
You can get some more details about the announcement from Kim Cameron's blog post CardSpace / OpenID Collaboration Announcement
which has more details on which companies are collaborating with Microsoft in this effort.