Please be advised that Comcast has now opened its Xfinity WiFi hotspots to the general public. This, and additional measures, are detailed in the attached press release, and also  available here . The relevant portion is as follows:
Xfinity WiFi Free For Everyone : Xfinity WiFi hotspots across the country will be available to anyone who needs them for free – including non-Xfinity Internet subscribers. For a map of Xfinity
WiFi hotspots, visit Once at a hotspot, consumers should select the “xfinitywifi” network name in the list of available hotspots, and then launch a browser.