I've got a client with a product innovation that requires me to get
quickly up to speed on GPS/RFID to establish location. The idea is to
map a building (like an office tower, school, factory, etc.) and get
precise coordinates on people and things within that field.  I'm
looking to find out the current limits of the technology, what the
best trade-off between cost and resolution (centimeter or inch is
desired), and who's making what pieces. Can you help me start off on
the right track?

That might include:

A short list of experts, their domain of knowledge, and contact info

Companies that produce the devices that "sense" where things are,
organized by resolution (smaller is better, for example satellite
imagery is available to the general public at about 1 meter = 1
pixel).

Examples of product solution sets (maybe from consultancies) that do
what I'm asking.

Please ask if you have questions. Thanks.

Hi,
This is not to discourage you but i dont believe in GPS to do what you
want. GPS as you might know was originally made for military purposes
and would perform accurately to meters only if on open air. I have
worked on GPS for a couple of years and the GPS service avialble for
commercial purposes is very inefficent for your application. Only
differential GPS can solve your problem, but its not available to the
public.
I recommend not to rely on GPS for this project.

what you are wanting is to use "RFID Triangulation" which measure
signal latency of RFID tags from different locations and uses those
values to approximate the location.
http://www.jefflindsay.com/rfid2.shtml
that page has more information on the subject....