If the core of the OS gets updated, it's not unrealistic to require restart of it in order to start using the updated version. In Linux, that means the kernel

If the core of the OS gets updated, it's not unrealistic to require restart of it in order to start using the updated version. In Linux, that means the kernel and possibly few other core packages, and if that's unacceptable for any reason, there's the magic of http://www.ksplice.com/ http://www.ksplice.com/ to help you out. As an example, I have just updated the (intel) video driver in my desktop Ubuntu 10.10, and got no prompt to reinstall (arguably, it might be good for the system to ask me to relogin in order to start using the updated drivers - but it didn't). So in this regard, I haven't seen Ubuntu behaving worse than any other Linux distributions (and, I suppose, other normal operating systems), and behaves quite reasonably.