The migration of Dark Souls from Games for Windows Live to Steamworks is still planned, but for next month. When news of FromSoft’s plans to move the PC version of Dark Souls to a Steamworks system (like the sequel) first appeared, the proposed schedule was November.
In an update made to the Steam announcement page, FromSoft now say they are “targeting” December. Here’s what it says:
– UPDATE 11/25/14 –
We are working hard to finalize the process to move your Dark Souls: Prepare to Die saves and achievements to Steam. We need to conduct additional testing and we are now targeting December to begin this process. We’ll have more information in the coming weeks. Thank you very much for your patience!
Those who only own the game on Games for Windows Live (ie; it’s not in your Steam library) will need to redeem some sort of GfWL “token” in order to claim a Steam version. There’s more on that subject in the link above.
As far as I’ve been able to ascertain (and I’ve asked Bandai Namco about this too,) if you already have Dark Souls: Prepare to Die Edition in your Steam library, all you need to do is wait for the December update.