Erick Schonfeld points to Chartbeat's realtime snapshot of what activity on al-Jazeera’s English website on Friday when Mubarak resigned:
Concurrent realtime visits spiked from about 50,000 right before noon ET to 135,371 when the snapshot above was taken. The number of people simultaneously on Al Jazeera’s website kept going as high as 200,000that was at any given second, and translated into millions of people watching on the Web. (And this was on top of already higher traffic which had risen 2,500 percent earlier during the uprising).
Schonfeld emphasized Twitter's role in directing people to al-Jazeera:
If you drill down into the report for the article, “Hosni Mubarak resigns as president,” a full 71 percent of traffic at 11:40 AM ET came from social media. ... And what was the biggest source of social media traffic? It wasn’t Facebook. It was Twitter (followed by Reddit). When it comes to spreading realtime news, the social revolution is very real and Twitter is in the vanguard.