This is a totally useless blog entry, I admit.  But, I finally figured out what all the different lanyard colors mean here at the PDC.

Black – PDC Crew
Blue – Microsoft (Staff)
Green – Attendee
Orange – Sponsor
Purple – Exhibitor
Red – Media
Yellow – Speaker

Did I miss any colors?  I don’t think so.  Although in certain lighting it’s hard to tell the yellow and the orange lanyards apart.