You need to think of your VMPlayer virtualized hardware as an independent computer, running it's own independent operating on it's own hardware. That's the way virtualization works!
Technically the HOST doesn't even know it's "running" the other computer, so it's not going to treat it differently. The same is true for the GUEST operating system: you are running a "vanila" operating system, it has no reason to treat it's HOST computer differently, to the GUST the HOST is just an other computer accessible through the local network.
That being said, you can re-write your question like this:
I'd like to create an app that when run from one computer will create a shared folder to a known location on an other computer. One computer would be running Windows XP 32 bit, the other would be running an other version of Windows, probably Windows 7 x64
The answer: Of course you can't do that: it would create a security breach! If you're able to create the shared folder, anyone's able to create a shared folder. Anyone could create a shared folder to any location on your machine!
To wrap this up, if you could run your application on the HOST, not the GUEST, you might be able to use VmWare API to do something, but AFAIK the API is not available with the free VmPlayer. Also, if you could run applications on both guest and host you'd be able to do whatever you want.