Or you could just use OpenStreetMap which, y'know, gives you access to the Actual Map Data rather than having to reverse-engineer it from the rendered image...
That's true, although perhaps missing the point of the article. The example lets you used any particular image, rather than having to (for example) pull GeoJSON of the extent area, etc. It's a sweet hack.
If only there was something like maps.google.com for OSM. Yes, there's openstreetmap.org but that doesn't have directions or location sharing. Also, if people started using it like maps.google.com, I'm sure the OSM project wouldn't be too happy, seeing as how tile serving on such a scale gets expensive fast.