We are currently developing a mobile game with Unity3D. To get daily builds we already set up a Jenkins build server on a hosted virtual server which has no graphics card.
This caused some problems when we tried to activate our Unity PRO license to run the script which builds our players because the activation is only possible via the Unity editor which tells you “Failed to initialize unity graphics.” if you have neither DirectX nor OpenGL.
We found a workaround in the end, but it took some time and energy. So I decided to share our experiences, hopefully it will save some of you some precious coding time: http://www.slashgames.org/unity3dwithoutgraphics/
I would be very happy if you leave a comment after reading, so I know if the article is helpful and thus worth the effort. If it is I’ll try to share some more experiences during our development.