Mike,
First, the unit listed here is USB, which most modern EFIS systems have, so if a EFIS manufacturer wanted to write a driver, they could probably use the unit.
However, the coverage in the USA would be awful.
This is nothing like a Zaon. Zaon can pick up any transponder, and it can estimate how far away and what direction the traffic is by using multiple antennas. The accuracy of this is questionable, but it can pick up any transponder equipped plane as long as something interrogates the transponders, which could be an airliner with TCAS.
However, a 1090ES receiver is totally different. They work off the fact that a ADS-B compliant Mode-S transponder actually encodes the location of the aircraft right in the response. So these receivers don't work at all unless the other aircraft is equipped with a Mode-S, 1090ES transponder. So you'll see all the heavy iron, but not a lot of GA planes are equipped this way. Mode-C airplanes and airplanes equipped with a UAT will be invisible. Interestingly, 1090ES transponders do not need to be interrogated, they transmit their position all the time even if you are in the middle of nowhere.
Now, with the FAA's ADS-B ground stations, you theoretically can get Mode-C and UAT aircraft, however, your aircraft itself needs to be equipped with a certified ADS-B transmitter, either in the form of a UAT or a Mode-S transponder. Unless you have this on board, the ground stations won't send traffic up to you so you can only see 1090ES targets (A lot of those will be Dynon transponders!).
Given that 1090ES can't do weather, I think the focus of most EFIS manufacturers in the USA is on the 978MHz UAT link, which gets you both weather and traffic at a price that is not much more. It won't get you accurate traffic without ADS-B equipped on the plane either though.
There is a fairly common RS-232 format that most EFIS units support, which is the traffic format the Garmin GTX-330 transponder outputs. This isn't a perfect traffic format, but it does allow someone to make a traffic device that sends data to EFIS units.
--Ian Jordan
Dynon Avionics