For the server, its the same deal as always. If your using bukkit it may even update it for you. And the client updates the same way as normal. So... nothing changes. Except that everything is a little less accessible unless you know how to use linux.
Total file sizes:
Client - Base files are 70MB + drivers, which for Nvidia is another 30MBs. So for my computer, 110MB total.
Server - Base files are 50MB