I, too, have been looking for a wedding coordinator in that area.
Here are a few I've come across (I just contacted them as I am early in my quest for wedding plans but will be happy to share any info I get!)
Home
Weddings on the Beach, Weddings in Mexico, Weddings in the Caribbean, Weddings in Riviera Maya, Weddings in Playa del Carmen
About Us Weddings in Playa Has Experienced Wedding Planners to Coordinate Destination Weddings, Receptions and Mayan Ceremonies in Playa del Carmen Mexico
Good luck and let me know who you go with!
~A