Hi Seradus,
Sierra has said that there will be online multiplayer for all SKUs. I assume this means PC as well. So, hopefully that answers your question. If not, please clarify.
To build on this topic, and what I have pondered is possible Windows Live / Xbox Live cross-functionality. Just to clarify, I am just putting it out there. As far as I know, this is not what is planned, but in the interest of getting us talking about the game (in a good way) again, I thought I would put it out there.
I know a few games exist with this functionality. I think it would be great if we could bring the PC gamers and the Xbox gamers in the community under one virtual roof (so to speak).