Gog posted a statement regarding the D:OS release in their forum:

http://www.gog.com/forum/general/divinity_original_sin_on_gogcom_bstatus_updateb/page1

It seems that they are working to make the game available as soon as possible ("in the next few days") they say, which I presume to mean business days, so less the holiday weekend they could have something ready early next week.