The OpenNETCF.IoC Framework it is a public-domain-licensed (you can't get any more free and unencumbered than that) framework written in C# (framework version 3.5) that provides both inversion of control and dependency injection for applications running on any or all of the following platforms:
- .NET Compact Framework 3.5
- .NET Framework 3.5 or 4.0
- Windows Phone 7
It's roughly modelled after Microsoft's SCSF and CAB frameworks, but it's scaled down and optimized for running on mobile and embedded devices, plus I "fixed" stuff that I think the SCSF got wrong (like having a static, globally available RootWorkItem and the ability to insert IMessageFilters into the application's message pump).