After two month of studding I passed the VMware Datacenter Design test yesterday. thank you to all that share some information about the resources for the test. All the material is available on the VMware website. You will need to understand how to put solutions together and pay special attention to the formulas in each of the guides. Those formulas will come handy when you are taking the test as you will have to know how to do everything from scratch.
This test is more focus on the design than in the administration, so you need to understand the technical but it is more focus on how you as an Architect will design the virtualization strategies or design for a company or companies. You need to understand all the VMware products, (vSphere, vCenter, SRM, a little bit of Virtual Desktops just from a concept).
As others have posted time is not enough you have to be really quick on how to understand your concepts as you do not have enough time. Every second you waste can hurt you later. go thru the exam simulation and make sure you understand it.
The Fiber Channel and ISCSI guides are key as you need to understand them and know how to design solutions that will utilized those technologies. I will post later all the resources that I used.