AFAIK there is just one programmer, and he is on the LWJGL team but is by no means the only LWJGL developer.
There might be someone else working with him, I couldn't really find anything about it.
EDIT: apparently there are 2 people, Cas & Chaz:
http://www.javagaming.org/index.php/topic,23005.msg190715.ht...
And in that thread he did confirm they only make $250/month, split two ways. That's sad. I bought their first game years ago (I forgot it's name, but it doesn't appear to be for sale anymore). It was really good.
Alien Flux. Thrice cursed. Mention it not.
Why?
Total failure of a product which did almost everything just exactly wrong. Wasted a year of my life on it before I realised it was a total flop.
Also, PuppyGames are the people responsible for LWJGL[1], which IMO is the best way to go for making games in Java.
[1] http://www.lwjgl.org/