I am doing lot of work with Cardspace and Infocard.
If you are trying to get the Infocard Labs working from the Vista Beta2 release of Infocard (earlier this year) with the latest June CTP of the .NET framework you’ll find the code doesn’t work with the latest CTP. This is due to a number of breaking changes that were implemented in the latest CTP.
You’ll find a list of these here: Breaking changes.
I found the most important one was the change from System.ServiceModel.Identity to System.ServiceModel.EndpointIdentity.
That should keep all four wheels on the road until the next CTP.