For some reason, I found that running the documented archetype from the quick-start page brought back an earlier version of the archetype (0.1.2-incubating rather than 0.2.0-incubating). No idea why. Explicitly specifying the archetypeVersion caused Maven to do the right thing.
In case this happens to others, suggest that our quickstart page documents the current version, ie includes an "-DarchetypeVersion=0.x.x-incubating". This can be automatically calculated using $
and renaming to an .apt.vm.