Here is what I did to make Unity play nice with ASP.NET Identity 2.0:
I added the following to the RegisterTypes method in the UnityConfig class:
container.RegisterType<DbContext, ApplicationDbContext>(
new HierarchicalLifetimeManager());
container.RegisterType<UserManager<ApplicationUser>>(
new HierarchicalLifetimeManager());
container.RegisterType<IUserStore<ApplicationUser>, UserStore<ApplicationUser>>(
new HierarchicalLifetimeManager());
container.RegisterType<AccountController>(
new InjectionConstructor());