I heard they were working on a new version (not mod, an actual new version!) Harpoon 4. Just went to the official Ubisoft website, and they state:
"Larry Bond's™ Harpoon™ 4 PC Feb. 2004 Simulation E $39.99 "
However, that was spring of 03, Fall of 03, Spring of 04...
Don't hold your breath, I don't see this moving quickly at all. However, I was a big fan of the first Harpoon so I am waiting patiently.. Here is a link to their website......
http://harpoon4.ubi.com/US/