ServiceResolverAdapter: Allows you to use the ASP.NET MVC DependencyResolver for ASP.NET Web API

ServiceResolverAdapter.cs

using System;
using System.Collections.Generic;
using System.Web.Http.Dependencies;

public class ServiceResolverAdapter : IDependencyResolver
{
    private readonly System.Web.Mvc.IDependencyResolver dependencyResolver;

    public ServiceResolverAdapter(System.Web.Mvc.IDependencyResolver dependencyResolver)
    {
        if (dependencyResolver == null) throw new ArgumentNullException("dependencyResolver");
        this.dependencyResolver = dependencyResolver;
    }

    public object GetService(Type serviceType)
    {
        return dependencyResolver.GetService(serviceType);
    }

    public IEnumerable<object> GetServices(Type serviceType)
    {
        return dependencyResolver.GetServices(serviceType);
    }

    public IDependencyScope BeginScope()
    {
        // This doesn't support child scopes, so we simply return 'this'.
        return this; 
    }

    public void Dispose()
    {
        // When BeginScope returns 'this', the Dispose method must be a no-op.
    }
}

public static class ServiceResolverExtensions
{
    public static IDependencyResolver ToServiceResolver(this System.Web.Mvc.IDependencyResolver dependencyResolver)
    {
        return new ServiceResolverAdapter(dependencyResolver);
    }
}

Small changes to make it work with MVC 4 final (RTW). Also added namespaces for clarity.