ADAMSyc allows you to sync AD users with AD LDS - more at http://blogs.msdn.com/b/jeff/archive/2007/04/01/synchronize-active-directory-to-adam-with-adamsync-step-by-step.aspx - however this does not include passwords.
To synchoronize passwords, you would need to implement additional mechanisms that provide this functionality - such as FIM 2010 (http://technet.microsoft.com/en-us/library/jj590203(v=ws.10).aspx )
hth
Marcin