Muki Haklay has an interesting post about the state of play regarding VGI (volunteered geographic information) in Haiti and possible conflicts between OpenStreetMap and Google.
Here is a comparison map of coverage, where “yellow means that there is a better coverage in Map Maker, and blue means that there is a better coverage in OpenStreetMap. The difference between the two datasets is expressed in metres.”
there are differences between the two sources of data, and these may matter as the relief work is carried out. The evaluation question is: for each grid square, which of the datasets contains more information in terms of roads length?