I came across another interesting remote control solution for Windows Media Center. This one called Meanie works on most modern mobile web browsers, the developer has tested it with an iPhone but it should work on Android and Windows Phone 7 as well.
On the Windows Media Center PC you install the server component and then just browse to the service from your phone. Its nice way of having a mobile device remote control but without the need to install anything on the phone.
The service is in beta at the moment and you can download it for free from the developers site