Hi Elkin,
Shouldn't be surprised to know that SAP is not offering certification for MDM right now. Folks working on current MDM version are awaiting to appear for MDM 7.1 certification which is not available from early 2010 (mere guess). Hope SAP will revive plans for MDM certification and come up with some solution at the earliest. For now, Just keep learning and wait for SAP to announce. Hope for the best!
Regards,
Kasim Ali