If you go to the Yahoo Maps mainpage and enter an address, you'll be given a map of the location. Along the right-hand side select travel and transportation to expand the menu. The first item on the list is ''Wi-Fi Hotspots'' although the site is experiencing a few glitches so the text is not diaplyed. Click the bubble and you'll see the map light up with the Intel Centrino logo. Next, you'll want to click the bubble next to ''SBC FreedomLink Wi-Fi'' for all SBC-driven hotspots. While no map lists all hotspots, this is the most comprehensive one I've found.
Hope this helps,
John