A lot of websites are joining the SOPA blackouts or the protests today, many are large sites, such as Mozilla or Wikipedia, so they've taken precautions to ensure that the move won't prove detrimental to their ranking.
Even smaller sites that have used
Google's guidelines should be safe. But there are plenty of sites out there that haven't implemented a blackout correctly and even the ones that did will see a slowdown in crawling rate for a few days after the blackout.
To minimize this, Google has slowed down the crawling rate of the Googlebot for today for everyone.
"We realize many webmasters are concerned about the medium-term effects of today's blackout. As a precaution, the crawl team at Google has configured Googlebot to crawl at a much lower rate for today only so that the Google results of websites participating in the blackout are less likely to be affected," Google's Pierre Far
wrote.