I have a user case (my case) for you:
In the evening and even at night I use my computer to play music till certain time (like radios sleep function). Then the computer will be shut down so I can take it with me to work/university in the morning. And it is extremely important for me to have the sound muted when I start the computer there (I shouldn't disturb others with sounds). So I wrote an application that works almost like any other timed shutdown programs with an option to mute sound before shutting the computer down. The program is freely available on the web and has proven to be very popular in Estonia .
Now can I use the same kind of functionality in Vista? And will it be difficult to port this application to Vista or will it work without modifications? I guess modifications will be nessecary as otherwise the program would mute just itself.