I too had to enable roaming profiles support in the Workgroup settings of the SME 5.1.2 web manager to enable the home folder mapping via logon script.
However, I have an extra home folder mapping, 'z:', along with the 'h:' folder. My netlogon.bat does not specify this net use z: command and I have done a net use z: /delete and rebooted only to have it reappear.
Very odd.