MVVM - 在Silverlight和WPF之间共享/重用ViewModel

Is it possible to share viewmodels across platforms - WPF/Silverlight? I started down the path of putting my VMs in a separate assembly and soon came to ICommand - which then led me to ask this question? Is this possible, and if so is it good to do so? We have a possibility in the future of having a client application for WPF and Silverlight, so I would like to not have to duplicate VMs for both.Is it possible to share viewmodels across platf