It's been almost a full day now and the nation of Syria remains completely cut off from the rest of the Internet (and by extension, the outside world.) Internet analysts who watched the collapse in real-time think they've figured out how it was done.
The Syrian government claims that "terrorists"—their standard euphemism for the rebels—cut the major cables supplying internet connections to the country. That's an unlikely scenario for a couple of reasons. For starters, the Internet is the rebels' most important communication tool, used to talk to each other and to spread word of the conflict around the world. There'd be no advantage for them to disable their most effective propaganda tool. (Although, the Syrian state media website is also down.)
Furthermore, there are four actual physical cables that deliver connections from the global Internet to Syria. (Image via Renesys.com) Three of them are underwater, in the Mediterranean Sea. The other comes across the Turkish border. To completely stop the Internet in the manner observed, all four would have to be severed simultaneously, an unlikely logistical challenge for the rebels, and one that still wouldn't fully explain the systematic shutdown observed by technology companies elsewhere.