Flightaware does. I used their gear in part shaking down my Skybeacon Anonymous mode posts.
My SDR, Flightaware filter and basic +5dbi SMA antenna, same as you would find on a Stratux, records planes with UAT to 30+ NM at 2000+ AGL regularly. Just plugged into my phone, on the ground, not even on a highpoint in the open. The 1090 antenna gets enroute jets out to 120+ NM.
I am unsure of how 978mhz UAT recording will catch on vs existing 1090mhz ES/ADS-B out recording. It takes an extra receiver (SDR), extra antenna, extra USB port and extra run of line to the antenna.
31 January 2019-
FlightAware is pleased to announce the availability of a 978 MHz antenna designed for receiving UAT978 signals. This antenna is a similar design to our very popular 1090 MHz antenna and is offered at a similar price point. We think it offers a great value to enthusiasts that wish to experiment with UAT reception. We are offering a limited quantity of these antennas via Amazon USA to hobbyists that have built or are interested in building sites that use the “dump978” software to track aircraft that use that alternative ADS-B technology in the USA. Also remember that our bandpass filter can be used with this antenna as it is designed to pass both 978 MHz and 1090 MHz signals. Please note that this is not a dual-band antenna design and is specifically for use on 978 MHz only. You will want to use a separate receiver such as the original (Orange) Pro Stick USB RTL-SDR device to receive 978 MHz. The Pro Stick Plus is not compatible with UAT 978 reception. This is a limited quantity offering while we assess the level of interest in 978UAT among the hobbyist community. We will evaluate increasing future supply of this product based on the level of interest.