The wikipedia link does not work. Cutting the latency in half is not saying a lot, because satellite connections have huge latency on the upstream. Any concrete data on what the latency will look like?
We don't know what the latency will be until they launch but, theoretically, since they're launching the satellites into Middle Earth Orbit, the signal only has to travel half as far as the current satellites up in Geostationary Orbit. Google is also offering Google Apps and perhaps the caching servers we've heard in recent news to the local ISPs.