Hank Williams, on his blog 'Why does everything suck?', explains why the fact that Adobe has added a P2P component to the Flash player will kill content delivery networks, among other things.
What is even more interesting than cloning existing applications, is the innovation that will be unleashed by making p2p technology an assumed part of the web protocol stack. For example, it will be a few hundred lines of code to write an AIR application that will allow you to drop a file onto an icon and have that file appear on your buddy's computer.
This could become quite interesting.