I was trying to use Unity 2.0 beta 2 for Silverlight in my Windows Phone 7 project and I kept getting this crash:

Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.DynamicMethodConstructorStrategy() + 0x1f bytes

Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy.DynamicMethodConstructorStrategy() + 0x1f bytes   mscorlib.dll!System.Reflection.RuntimeConstructorInfo.InternalInvoke(System.Reflection.RuntimeConstructorInfo rtci = {System.Reflection.RuntimeConstructorInfo}, System.Reflection.BindingFlags invokeAttr = Default, System.Reflection.Binder binder = null, object parameters = {object[0]}, System.Globalization.CultureInfo culture = null, bool isBinderDefault = false, System.Reflection.Assembly caller = null, bool verifyAccess = true, ref System.Threading.StackCrawlMark stackMark = LookForMyCaller)  
mscorlib.dll!System.Reflection.RuntimeConstructorInfo.InternalInvoke(object obj = null, System.Reflection.BindingFlags invokeAttr = Default, System.Reflection.Binder binder = null, object[] parameters = {object[0]}, System.Globalization.CultureInfo culture = null, ref System.Threading.StackCrawlMark stackMark = LookForMyCaller) + 0x103 bytes 
mscorlib.dll!System.Activator.InternalCreateInstance(System.Type type = {Name = "DynamicMethodConstructorStrategy" FullName = "Microsoft.Practices.ObjectBuilder2.DynamicMethodConstructorStrategy"}, bool nonPublic = false, ref System.Threading.StackCrawlMark stackMark = LookForMyCaller) + 0xf0 bytes mscorlib.dll!System.Activator.CreateInstance() + 0xc bytes 
Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.ObjectBuilder2.StagedStrategyChain.AddNew(Microsoft.Practices.Unity.ObjectBuilder.UnityBuildStage stage = Creation) + 0x1d bytes    
Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.Unity.UnityDefaultStrategiesExtension.Initialize() + 0x6c bytes   
Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.Unity.UnityContainerExtension.InitializeExtension(Microsoft.Practices.Unity.ExtensionContext context = {Microsoft.Practices.Unity.UnityContainer.ExtensionContextImpl}) + 0x31 bytes  
Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.Unity.UnityContainer.AddExtension(Microsoft.Practices.Unity.UnityContainerExtension extension = {Microsoft.Practices.Unity.UnityDefaultStrategiesExtension}) + 0x1a bytes 
Microsoft.Practices.Unity.Silverlight.dll!Microsoft.Practices.Unity.UnityContainer.UnityContainer() + 0xf bytes 

Thinking I could resolve it I've tried a few things but to no avail.

Turns out that this is a rather fundamental problem and my assumption that Windows Phone 7 is Silverlight 3 + Some other stuff is wrong. This page describes the differences between Mobile Silverlight and Silverlight 3.

Of particular interest is this:

The System.Reflection.Emit namespace is not supported in Silverlight for Windows Phone.

This is precisely why Unity is crashing on the phone, DynamicMethodConstructorStrategy class uses System.Reflection.Emit quite extensively...

So the question is, what alternative to Unity is there for Windows Phone 7?