If you are excited about CardSpace and wants to dirty your hands with .NET 3.0 RC1 bits, you will realize that CardSpace samples are broken. What "broken" means here. All of those samples are meant to work with "Self Issued Cards". But due to change in namespace from RC1 bits, CardSpace Identity selector prompts for a managed card.

Current samples uses the following

<object type="application/x-informationcard" name="xmlToken">
<param name="tokenType" value="urn:oasis:names:tc:SAML:1.0:assertion" />
<param name="issuer" value="http://schemas.microsoft.com/ws/2005/05/identity/issuer/self" />
<param name="requiredClaims" value="http://schemas.microsoft.com/ws/2005/05/identity/claims/givenname
http://schemas.microsoft.com/ws/2005/05/identity/claims/surname
http://schemas.microsoft.com/ws/2005/05/identity/claims/emailaddress
http://schemas.microsoft.com/ws/2005/05/identity/claims/privatepersonalidentifier" />

But starting with RC1 you need to change "schemas.microsoft.com" to "schemas.xmlsoap.org". Just a find and replace is good enough.

So with the changes it should look like

<object type="application/x-informationcard" name="xmlToken">
<param name="tokenType" value="urn:oasis:names:tc:SAML:1.0:assertion" />
<param name="issuer" value="http://schemas.xmlsoap.org/ws/2005/05/identity/issuer/self" />
<param name="requiredClaims" value="http://schemas.xmlsoap.org/ws/2005/05/identity/claims/givenname
http://schemas.xmlsoap.org/ws/2005/05/identity/claims/surname
http://schemas.xmlsoap.org/ws/2005/05/identity/claims/emailaddress
http://schemas.xmlsoap.org/ws/2005/05/identity/claims/privatepersonalidentifier" />

While writing this post, neither sample posted on www.identityblog.com has been updated nor any of the other samples available, including SDK documentation.