I receive a few emails a week regarding this, so I want to clear up any confusion about the various versions of the PayPal Pro module that are available.  

I don't believe this module is in development any longer, but you have two other options.  If you are looking for the community developed version, it is here:
http://www.oscommerce.com/community/contributions,3647

and the support thread is here:
http://forums.oscommerce.com/index.php?showtopic=174981

PayPal's official version, that you'll find in the link posted by jasonabc, is v0.7.3 of the community-developed module found in the link above, with some modifications.   0.7.3 is a stable, but old release and doesn't include features such as order item lists being sent to PayPal, CCGV support, improved error handling, etc.

Also note that since PayPal handles all development of that fork, all support questions regarding it should go to them.  Hopefully that clears up any confusion regarding the various versions available.