Security Token Service (STS) and Relay Service are available in beta for developers building Web applications. The services are part of Microsoft Live Labs’ “cloud services,” or early test-phase technologies. Developers using them must use browsers with support for Microsoft’s still-to-be-announced InfoCard, such as Internet Explorer 7 Beta 2 or later. Gartner’s John Pescatore: “How do you know you can trust that code and that there aren’t vulnerabilities built into it?””]
Source: https://www.darkreading.com/analytics/microsoft-serves-up-security-services