Ray Saintonge wrote:
What this issue all comes down to is what do we want on a map and in how much detail. Do we want an overlay system, and is it technically feasible?
An "overlay" system, i.e. one based on layers, is inevitable. Some layers, e.g. satellite images and vegetation types, are best represented as rasters, while others, e.g. rivers, borders, roads, are best represented as vector data. These are GIS fundamentals that you are hardly going to change.
I found out that the phrase to google for is "collaborative mapping". Much seems to be happening in and around London. Knowhere.co.uk is a rather old site, not wiki, and only has 2000 nodes (city names). OpenGuides.org is a little newer, wiki-based. Confluence.org has photos from many of the 360 x 180 points on the globe where integral degree lines intersect. Even people from the British Ordnance Survey (ordsvy.gov.uk, the governmental mapping agency) are interested in playing along these lines, although they haven't promised to donate any mapping data. "Collaborative" doesn't always mean "free" (in either sense of the word).
If you look at my May 1994 project "Real World Interface" and imagine there are "edit this page" links on every page (as there aren't), you get *one* idea (not the only one) of what a geo-wiki could look like, http://www.lysator.liu.se/rwi/ (click Sweden and the southern third to get started).