I came across a very succinct summary of these technologies and the scenarios they support over at Matthew Gardiner’s blog:
Information Cards provide a very elegant system for use cases which require and/or benefit from explicit user participation. With Microsoft’s impending release of supporting server side tooling, it will be an important force in Web identity management for many years to come. However, for applications for which explicit user participation is unnecessary or counter-productive – simple Internet SSO being the goal – SAML remains the best choice. OpenID’s focus remains on easing access to applications for which assuring true user identity is not really necessary.