The folks over at WebmasterWorld started a new thread named One year anniversary of the "Florida" Update in preparation if it "can happen again?"
Well can it happen again? Based on history, it will. Google has often made major algorithmic shifts it the core of the algorithm right before the big purchase season of Christmas and New Years. As more and more sites become involved in the search engine optimization craze, more and more people realize the direct impact of these changes to the business's profits.
Of course this is why many experts, like Danny Sullivan, believe you should not have all your eggs in one basket. Play both the PPC game and the SEO game, and don't forget about last years customers. Email marketing, and the other types of online marketing efforts can be huge.
How are you preparing? :)