I'm working on a site which has a members section. I have extended the standard member type with some custom properties, one of them being a Media Picker - Image Only for choosing picture. Inspecting the IMember object, the "picture" property contains the Udi of the Media Node, but GetValue< returns null.

@{
  int totalRecords;

  var members = ApplicationContext.Current.Services.MemberService.GetAll(0, 500, out totalRecords);
}

<ul>
  @foreach (IMember member in members)
  {
    var picture = member.GetValue<IPublishedContent>("picture");

    <li>
        <div class="post_thumb">
            @if (picture != null)
            {
                <img src="@picture.Url" class="avatar photo" />
            }
        </div>
        <div class="post_title">
            <strong>@member.GetValue<string>("name")</strong>
        </div>
    </li>
  }
</ul>

This work around solves it, but it's not a very nice solution compared to casting it right away:

var pictureUdi = member.GetValue<Udi>("picture");
if (pictureUdi != null)
    picture = Umbraco.TypedMedia(pictureUdi);