I am looking for sites that do a good job of reviewing / documenting current LTE data coverage in the US. Where do the carriers have coverage maps and plans for build out documented? Also, are there any independent sources that measure actual performance and coverage so that we can educate ourselves about the options available for data on the new iPad?
Not much in the way of a major community database of real-world speeds, sadly. Here are some other resources:
You might also use the FCC's GIS data to find out more about what towers already exist. Presumably, they're not going to build new towers for LTE - just add antennae to existing sites.