Any chance we will see the Geneforge series for on the Mac ?

Considering the Geneforge games (as well as any other made by Spiderweb) were originally made for mac, I don't see why not.
I'm not sure why GOG only provides the Windows version, but it should be fairly easy to get the mac version as well.

Send a support ticket and ask them. There's a good chance that they might reply.

Yes, yes there is when exactly I don't know but it's supposed to be soon from what I seen in post on Spiderweb's official Facebook when they were talking about the release of Avernum on GOG

"We are thrilled to announce that the entire Avernum saga (Avernum 1-6 plus Blades of Avernum) is now available on gog.com for the low price of $12.99, with a 33% discount for the first week. Even better, all of these games are available for both Windows and Macintosh! (Avernum 1-3 for the Mac are the Windows versions running under emulation, but they will work on newer versions of Mac OS X, while our site's versions won't.) Gog.com is a great site and we're very pleased to gradually make our games available there. The Geneforge Saga is already for sale on that site, and the Mac versions of the Geneforge games are coming soon.."

https://www.facebook.com/SpiderwebSoftware

It should be out for the Mac tomorrow, check the last paragraph: http://www.gog.com/news/january_mac_game_update_10_new_additions

Bow chicka wow wow!

Perhaps they had problems testing a few of them that took longer than anticipated?

Yay, it's out!