http://crowncastle.com/das/index.aspx
Looks like they are ramping up cell coverage in addition to the WI-FI, I wonder which carriers? We have a DAS from a different vendor in our hospital and pipe in Verizon and AT&T. We provided the DAS and they provided all of the hardware to connect to their networks. The DAS is not cheap so if they are doing this everywhere on property I know where a chunk of the 1 billion went. I have heard unconfirmed stories where the carriers will pay for access to your DAS if are bringing service to enough customers that would not have had it otherwise.
Edit:
that's a leap on my part assuming cell coverage, they can also pump other signals/frequencies on the DAS (we do) so it could be a proprietary system or both. That's the nice thing about DAS is you can run multiple signals on one antenna system as long as it is engineered for it.