A very interesting article on using WPF to display presence by Erik Klimczak from Clarity Consulting. It goes more into the WPF side, than the actual presence, but you need to know how to make your presence bubbles look good too! I love the example of creating a screen saver out of it, It doesn't currently show actual users presence, but the article challenges you to add that your self. I'd also like to extend that challenge! Hint: I'd look into using the Communicator Automation API first.