Tedster, I agree. I'd expect to see a fair bit of tweaking of the algo over the next few weeks as it gets refined. I saw the same with the big local update that happened in late Oct. last year. The results now are substantially different than when the algo change first kicked in.
It'll be interesting to see if anyone comes out with a good analysis of WHY eHow didn't get hit and the others did, beyond Google conspiracy theories. I've heard people postulate that it's the amount of duplicate content but to my knowledge a lot of the other sites that got hit had mostly unique, though low quality content. My suspicion is that it's mostly user behavior or link profile that saved them as I know some of the SEOs that were working on the sites that got hit and they are extremely knowledable. That leads me to believe that it isn't on page or architecture issues, nor is it purely uniqueness of content.