I thought i was in another preview but from what i can tell the new page screenshot features are going live to all datacenters. Their preview is different (and better) than what other search engines have implemented in the past because their content previews show real text and show where its found on the page...
Something I think this helps prove to me (although I already really believed it was being done) is that Google at least is in fact able to interpret and understand the complex positioning of elements and that footer link detection is probably trivial to them
It will be interesting to see how hidden text appears in these previews and if spam results are easier to spot in SERPS. Something to note is that flash is broken in the previews so if your site uses flash and cares about the preview that much they may want to have styles that unhide the flash and have a static picture that can stand in so the entire site doesnt look broken do to the thumbnail not rendering the content for that embedded movie
What implications do you think the new preview has for SEO and SERPs? Do you think the big G is doing too much to copy Bing's tools? It seems like they found another tool that may be effective and updated it to the level that we have come to expect from Google.
Heres how you could do the alt HTML for a java applet