When I visit that page it tells me "OpenStreetMap powered by mapquest". Shouldn't that kind of be the other way around? I mean, in this case, mapquest is using the maps from Open Street Map, so IMHO, I'd say that OSM is powering Mapquest here.
Not that it matters much.
I do love Open Street Map though, also because it's so easy to contribute. I could very easily improve the map around where I live. One particular street for example has been closed off two years ago and OSM is still the only map that gets it right.
Also.. not particularly surprising. MapQuest hired one of OSM's community managers this summer. Good to see collaboration and innovation on top of good data.
The labels are choosen automatically by software. It is a bit of an outstanding issue has to how to make that work correctly with USA cities. The whole data set is a wiki, anyone can edit anything. It's not obvious how to place the labels in an objective manner.
There's some info here about how the US concept of "city" clashes with the UK concept, which was used as the basis of some data naming decisions, and the effect it has on the US map.
The various hiking and biking trails that I use are likewise far better detailed on OSM. They also have better maps of neat stuff like train tracks. Down to individual tracks at trainyards/stations in some cases.
If you zoom in far enough the trails are visible. Obviously, if the trail isn't mapped yet it won't show up. Feel free to add the trails that are missing!
Not that it matters much.
I do love Open Street Map though, also because it's so easy to contribute. I could very easily improve the map around where I live. One particular street for example has been closed off two years ago and OSM is still the only map that gets it right.