I have some wh sites with good content (flash, video embedded, etc.) that go viral like crazy on fb and get a lot of likes/shares. While going through them today, my PR extension in chrome showed PR 4 for one of the sites. I checked rest of the similar sites and some of them got PR too. And the only thing is that they got tonnes of fb likes and shares but no backlinks. Also they are just single-page sites. Here are their stats: Likes: 110k+ +1s: 1 Tweets: 156 PR 4 Likes: 15k+ +1s: 1 Tweets: 88 PR 2 Likes: 20k+ +1s: 0 Tweets: 81 PR 1 Looks like social media especially fb likes plays a pretty good part in SEO as we can see here site with single pages gaining PR with zero backlinks. Any thoughts on this?