no, I don't think there is a way to change every hosts file at once. Although you might try and create a so called "network boot". Not sure if it's the right term here, but basically when a computer is started, it loads itself locally, but all configuration is downloaded... I think this isn't possible xD
Simpler way would be to just write a simple program to check and download the hosts file each time the computer starts. So when you change it on the server, when each computer starts over again, it downloads the file... it's rather simple and I could churn it out if you need (get on IRC so we can talk if you like).