Good Topic Doc.
First, a kill switch for Egypt (or even China) is possible because of the way the Internet was implemented in those countries. But the way they can do it is not possible for the US. The Internet was created and DESIGNED in the USA to be redundant, and in most respects, it is. Other countries "tapped" into the Internet, so the government just has to kill the tap.
However, for all intents and purposes, if the government was given the authority, it could effectively shut down the Internet to all but the most diehard geeks. How?
The street signs for the Internet are maintained by a core of companies. And if they were to shut down their servers, no one could get anywhere unless they knew the IP address of where they are going! DNS people. And that is the achilees heel for the effective shutting of the internet. If the Root servers are shut down, you are going no where.
DHS has already done that by basically pulling some sites out of the DNS (supposed pirate sites). Bit Torrent has said they were looking at creating a P2P DNS for those sites shut down by DHS - and it is doable, but so far that is just a nice idea. it has not been implemented.
So Obama's "Kill switch" would be to pull the plug on the DNS servers. That would shut down the internet for not only the USA, but the world (with the exception of their country codes root domains).
Should the government have such authority? No. Government abuses everything it is allowed to do. If you cede that power to them, you have just lost another part of your rights, freedoms and liberties.