> I/O in nodejs is always asynchronous. I/O in typical .Net apps is almost always synchronous, due to programmer choice. This approach is followed in the vast majority of Asp.Net apps

Nitpick: actually Node lets you do synchronous IO (http://nodejs.org/api/fs.html#fs_fs_readfilesync_filename_op...). Sometimes you can chose to use synchronous IO, for instance to do something in the initialization phase of your server.