title: Intercepting dependencies in MEF
body: <p>Is it possible to intercept dependency requests in MEF before they get handled by MEF?</p>
  
  <p>This would be useful for implementing decorators and advanced lifetime management.</p>
  
  <p>Something like...</p>
  
  <pre><code>catalogue.AddInterceptor&lt;IExpensiveService&gt;(b =&gt; ... return from pool ...);
  </code></pre>
  
  <p>Or even...</p>
  
  <pre><code>catalogue.AddInterceptor&lt;IExpensiveService&gt;(b =&gt; new Decorator(b()));
  </code></pre>
  
  <p>(where 'b' is the underlying MEF resolution func for resolving the service)</p>