[wyattearp]

Recent research in South and Central America has been pretty exciting. Lots of researchers have been going there in the last few years, far more than in past decades. I wonder if any of it has to do with Zawi Hawas making it nearly impossible to get a permit to dig in Egypt?

Gotta dig somewhere, right?

[blam]

"I wonder if any of it has to do with Zawi Hawas making it nearly impossible to get a permit to dig in Egypt? "

I don't know.
But, IMO, there is a lot more here to be discovered. For example, there are more pyramids in Mexico than the whole rest of the world combined...yet, you mention pyramids and everyone immediately thinks of Egypt. Incidently, the oldest pyramid in the world is in Greece, the second oldest is in Peru (Caral), also, the largest.

[Fraxinus]

IMO, it is due to the less dramatic combination of more stability in south and central America along with new tools that the researchers have had ten years or more to get results from. It takes time from the ID'ing of a prospective site to the excavation, and even more time from the start of excavation to publishing in scientific (often very narrowly focused)journals, then even more time to publication for the general public.