ExCM 2010 can be used with the Active Directory Membership Provider. However, you will lose a couple of features that are available when using the SQL provider. First, here is some documentation on configuring the AD provider:
How To: Use Forms Authentication with Active Directory in ASP.NET 2.0
And here are some more details about its limitations:
- No administrative password change support – The Active Directory membership provider does not provide support for administrative password changes. The user must reset their own password with their password recovery information or an administrator must change the password from the Active Directory Users and Computers windows application.
- No last login or last password change date support --The Active Directory membership provider does not provide support to obtain the last login date or the last activity date for a given user.
- No role provider – .NET does not provide an Active Directory role provider. This means SharePoint and/or ExCM 2010 will not recognize AD Security Groups. Therefore you will not be able to use AD Security Groups to grant permissions to site and lists for extranet users. You will be limited to SharePoint groups only.
- No profile provider - .NET does not provide an Active Directory profile provider. This means SharePoint and/or ExCM 2010 will not recognize AD user profile attributes. This is really only a minor issue as SharePoint will not recognize (say from the User Profile Import) membership attributes even when a valid profile provider exists. As a result ExCM 2010 only has limited support for the profile attributes.