Some Holistic Design games may be on the way to GOG: http://grogheads.com/whatever/19833
Regarding this old info, some of these games were made freeware on Holistic Design website (Emperor of the Fading Suns, Machievelli The Prince, Hammer of the Gods, Battles of Destiny) so I guess they won't appear here.
Which is quite a shame. I just tried to install "Hammer of the Gods" and it seems the installer is not compatibe with modern OS.
Sad that they (apparently) never got to reach a deal with GOG. I'd sure buy their games here. :(
EDIT: well... its seems SCPM has explained why the game wouldn't install on the post below :P
Guess there may be some hope of the games coming here, after all :)