vSphere Client 4.1.0 Build 345043
VMware ESXi Version 4.1.0 Build 348481
And I THINK I'm using VMFS3 if I am reading this correctly, since I am not 100% sure how to view it (I'm looking under Software > Advanced settings under the Configurations tab of the server)
There are 3 settings in here, not sure if they are relevant to what you were referring to. I'll just attach a screen shot.
EDIT: After heading to that link you posted I found I have a Block size of 2 MB and a File System of VMFS 3.46