SOPA SEO: Googlebot to crawl at slower rate today

Based on my previous experience, yes it would have an effect. If it actually hit tens of thousands of websites, I'm sure Google would be willing to work with them. I'd imagine they might have backups of search results, or could nullify and re-scan the sites. Google has recently shown they have the ability to alter the page rank of various sites (ala Google+ results).

It would change the rankings.

I recently had a client site go down (amazon instance stopped, no notification). It was out of the index by the time we caught it day or so later. This site also happened to rank pretty well for a niche term.

The good news is that as soon as the site was back up, it was back in the index within a few hours. Not sure if that's a typical experience.

I see your point, but I think it is mainly because they don't want Wikipedia/etc to be de-indexed and not be #1 hit for EVERYTHING anymore. This protest is exactly that, a protest, a mere emulation of what could happen.

It's not about pretending the web is normal, its about ensuring that everything is back to normal tomorrow.