AD-LDS (ADAM) For Windows 7 is now available (Again).

Microsoft have reissued the AD-LDS (Lightweight Directory Services (ADAM)) application for Windows 7,  AD-LDS is a Lightweight Directory Access Protocol (LDAP) directory service that provides flexible support for directory-enabled applications, without the dependencies that are required for Active Directory Domain Services (AD DS). AD LDS provides much of the same functionality as AD-DS, but it does not require the deployment of domains or domain controllers. In environments where AD-DS exists, AD-LDS can use AD-DS for the authentication of Windows security principals. You can run multiple instances of AD-LDS concurrently on a single computer, and have an independently managed schema for each AD-LDS instance. 

http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=a45059af-47a8-4c96-afe3-93dab7b5b658