SevenCubed - 10:24 pm on Nov 16, 2010 (gmt 0)
in order to benefit from previews you must, at the very least, lift any restrictions on indexing images as a prerequisite
I can say that hasn't been necessary on my end. I have the images folder blocked in robots.txt to all crawlers including Google. I also have hot-link protection in place through Apache and yet still the sites on my server are generating previews. I can see that the Google web preview is being returned a 200 response when requesting the images so I really don't know how they are doing this but I have bigger fish to fry right now than to worry about a single engine stepping around explicit instructions to not crawl or link to server images.
But overall, as far as how to benefit from this I'm still assessing it myself. I don't think it's a totally bad thing or I would simply ban those web preview IPs at my firewall.
What I am realizing, based on my observations is that sites with flash and other technologies that generate blank areas are no doubt going to suffer. Casual users might think if they go to the site they will be required to install some sort of a plugin and just skip it rather than be bothered by it.
More than ever now, I think it will be important to present a visually appealing static presentation. At least for the main page anyway. For me that means business as usual because it is what I've always preferred. And also, Google is just one source of traffic. It still stands with me to design for the consensus and not get bogged down with trying to appease any one source of traffic. In the long run it balances itself out.