I have both iPod Touch and Zune. I always thought that Zune was better until I discovered the Apple Remote that let me use iTunes on my PC from my iPod Touch. Since I have my PC connected to my stereo, this great functionality is making my Zune HD looking
kind of obsolute. There is also a $0.99 App Called Tango the let you remotely control the iPod from another iPod or iPad, so you can connect your iPod to your stereo and leave it there, and then remotely manage it.
So please make this functionality available, the technology is already there. I also think that it will be great if the Zune HD could be a graphical remote control for the Media Center, showing which song is playing and stuff like that. And finally, if the
Zune could be hooked to the PC as a seconday display, it will be really great.
So far this has been the only functionality that I found better on iPod touch than on Zune HD, to remotely control PC software and other mobile devices wirelessly.
I doubt this will ever happen for the Zune HD due to the totally closed development platform for apps.
However, the functionality exists on Windows Phone 7 (and in previous versions going back many years to before the iPod Touch existed, for what it's worth) to control Windows Media Player/Media Center via a phone over WiFi or the Internet.
However, personally I find these solutions to be less useful than simply using a regular remote control with Windows Media Center or using DLNA to stream content from Windows Media Player to a second PC/TV/Bluray player, etc. (most TVs and Bluray players
these days are DLNA compliant).
There is also the option of the Zune HD dock, which lets you control a Zune HD with a little remote control while the Zune is docked and outputting sound/video to a hifi system or TV.