If you use SUS or WSUS you can force a reboot after installation if the
updates required one, alternativley you can use something like shutdown.exe
from the Windows NT resource kit or psshutdown.exe from Sysinternals.com.
I use the latter and have scheduled out of hours reboots of my servers, if
you are careful you can use one machine to fire off remote reboots from a
script (I use a batch file) in sequence. I do this so that only one machine
is rebooting at any time.