The SAP MM certification is based on about 4-5 weeks of SAP courses.
For more details of areas covered in exam, see this SAP webpage
- Select "SAP ERP" and "Applications" and "Application Consultant"
Good luck with exam post to comments below any feedback regarding format.
** update 19 Oct 2010 **
I see booking for certification can now be done online (via 3rd party).
Certification can also be done at other centers -- not just SAP itself.
From link above I was also able to get some sample question -- about 10 or so.