It is amazingly inconvenient that Apple's Snow Leopard does not mount NTFS volumes as read write. However as it turns out it is pretty easy to override this default functionality.

I put together two scripts that you can run in Terminal to enable and disable read/write for all NTFS volumes (and all users). You can download them below.

Download NTFS R/W Mac

I would recommend restarting the machine after running the enabling script. My laptop acted wonky when I tried to eject my first NTFS USB hard drive (crashed Finder). However after a restart it was fine.

Thanks to the forum post below for the meat of the script.

http://forums.macrumors.com/showthread.php?t=785376