Games for Windows Live is the gift that keeps on giving. First it was dead, then it was not dead, and now it's causing trouble from beyond the hypothetical grave in Capcom's Super/Ultra Street Fighter IV. Capcom announced that they were making the transition from GfWL to Steamworks a couple of months ago, and now that's it's happened all sorts of connection and lag problems are occurring. Ultra SFIV's Steam forums page is awash with posts detailing a cornucopia of issues, which mostly appear to be related to the game's netcode.
After a few worrying weeks where it seemed that the problems wouldn't be addressed, a representative for Capcom has taken to the forums to state that they're "aware of the online connectivity & perf issues with the game and are working to get them solved as quickly as possible. Our team will continue to monitor the threads for any other issues that may arise so keep the comments coming. We appreciate your patience and support."
A patch was issued a few days ago that appears to fix some of them, but it's clear there's still work to be done. In the meantime, if you have a problem with Ultra/Super Street Fighter IV since the switchover to Steamworks, the Steam Forums are the best place to let the developers know.