Bandai Namco haven’t forgotten about moving Dark Souls over to Steamworks, and according to their US community manager J Kartje hope to get it done fairly soon. Asked on twitter when the migration from Games for Windows Live might occur, Kartje replies that he hopes it’ll be “in the next week or so.”
He adds that he’s not heard an “official update,” but believes the target to be before 20 December.
The initial transition was scheduled to take place in November, but the last update from Bandai Namco stated that it’ll now be happening this month. Unless, of course, it gets delayed again.
@ChaosBahamut Hoping in the next week or so. I haven't heard an official update otherwise. I think the target is before the 20th.
— J. Kartje (@JKartje) December 5, 2014
The Steamworks version of Dark Souls will add Steam achievements, and hopefully make multiplayer somewhat more reliable than “not reliable at all.” Bandai Namco has said that saved games will be transferable between versions, at least for the first month or so. You can read more information about all that in this Steam forum post.