This is not terribly surprising, but is noteworthy.
The 2500 year old (Middle Preclassic) site of Zazacatla is not far from Mexico City, but has turned up artifacts and sculpture which look very much like those at Gulf Coast Olmec sites. Pictures can be seen in this slideshow. We've known about Olmec-style sculpture in the Central highlands, most famously at Chalcatzingo. But the striking similarities to classic Olmec figures is impressive.
Speaking of the Gulf Coast, the pyramids and structures at El Tajin are being destroyed by acid rain. This site is likely more important than we currently understand.