The basic idea of all three hacks is the same: fool your user’s web browser into thinking that the data is coming from the same domain as the web page.
My name is Andrew Turner - a neogeographer involved in helping build the geospatial web. I am the CTO at GeoCommons, and also co-founded Mapufacture, where we're building a system that makes it easy for people to build and share collaborative maps and customize their slice of the GeoWeb.