After 3 years you build a new computer...
Intel has announced that the number is 5% within 3 years may fail. The reality, according to what I've been hearing, is much higher. And also, it's not complete failure, it's degradation of performance. It still works, but less. You start to get data corruption, or your performance slows, or your drive won't read correctly, or write correctly. What I've heard is that the degradation is likely to occur on EVERY board with the chipset, but that complete failure is relatively unlikely. Essentially, you'll lose data but not the motherboard. Which, for a set of components designed for high performance, is not acceptable.
Every manufacturer is going to replace the boards. Most online retailers don't even offer the 1155 architecture anymore, and won't until new product arrives. I still think this is the way to go... the advancements in the SandyBridge architecture go well beyond just the overclocking capabilities of the K chips. The chipset outclasses the previous architecture in just about every way, see the details here:
http://www.anandtech.com/show/4083.
As far as this being a new thing, it's not. Chipset replacements and recalls have happened before, many times. Often there's a software fix, or the exposure is limited to only a certain subset of systems. This is the first time I've heard where a common component on
all boards with a single architecture (1155) have failed. It's unusual in that sense, but given that the chipset has only been public for about a month, it could have been much worse.