Now that things have quietened down a bit on this issue, I expect there are a lot of Sandy Bridge motherboard owners who are wondering, "I wonder if I should have registered my board anywhere", or "how will I be notified when a replacement is ready for me?"
Well, it may not be the same the all mobo manufacturers, but in the case of Asus UK, anyone who is at all concerned can call their Customer Services Dept on 0870 1208340 and select the 'other components' option.
I did this recently, and spoke to a very helpful agent in Estonia, who first checked my board's Serial Number, to confirm that it was actually one of affected ones and then, after taking my email address assured, me that my details will be added to their list and I would be contacted with further information in due course. He then gave me a call reference number, and again confirmed that the board will definately be replaced at no cost to myself.
You can't ask for more than that, at this time, I don't think.