The PC version of Battlefield 3 will receive a 2GB patch tomorrow, December 6, which includes several fixes and "most of the content for Back to Karkand." DICE notes the inflated size of the patch being due to Karkand is not ideal and it will aim to make DLC content an optional download in the future.
The bug fixes and balance tweaks are plentiful in the patch, but the one that matters to many has been addressed: "Tweaked Tactical Light so it is not as blinding over longer ranges." And, to think, after being blinded so many times we were getting really good at navigating through echolocation.
There's no mention of whether these fixes are also buried in the console download for Karkand. The "Back to Karkand" DLC will be playable tomorrow for PS3 and December 13 for Xbox 360 and PC.