As this blog has mentioned in previous post, Microsoft CRM Live uses the Windows Live ID to authenticate users. Often business need, multi-factor authentication. This is basically using more than one type of 'claim' to identify the user to the system. Examples are to combine name and passwords with another claim such as biometrics or smart cards, or the new Microsoft Card Space. Windows CardSpace is a client application that allows the user to manage 'digital' identities, InfoCards, and then use them in identity systems or to provide specific set of data to software services.  Currently Windows Live ID is in beta support of including CardSpace. This means you can use CardSpace to aid in multi-factor authentication for Microsoft CRM Live. Also, as the Windows Live team continues to add form factors, they'll be able to support other means of digital identity.  Here's a link to more information about CardSpace http://windowshelp.microsoft.com/Windows/en-US/Help/7dc9c520-9d16-473d-b21b-413ac7226fb61033.mspx.