Can Mac OS lion and Win 7 (Vmware Fusion) Access Fat32 Partition?
Is it possible? Yes

Based on your comment, why?

VMWare Fusion runs Windows 7 virtually. Therefore you don't need a partition for it, the OS will simply be installed in a Virtual File on your current HDD, which will grow based on how much space it is using up to the maximum set when you created the virtual machine. Fusion only allows you to use a partition if your using Bootcamp to run Windows already.

Furthermore, Fusion allows you to share folders on your OSX drive with the Virtual Machine directly, without needing to format a partition beforehand, and can also write to your OSX drive natively. 

Remember, you are basically running both operating systems at the same time, and Fusion, like Parallels, completely integrates and shares between the 2 operating sysems seamlessly.

What you are referring to in your question is dual booting using Bootcamp, where you can only access one operating system at a time, and no sharing is done.