GeOSM2 is a widget that adds a minimap to your sidebar(s) displaying the location where you posted the entry.
GeOSM2 will search your post for a set of tags. Entering geo_longitude, geo_latitude and geo_public will give you a coordinate and an acceptance from the blogger to use the location added. The iphone program (amongst others) will add these parameters if you tag the entry.
The map is loaded from the OpenStreetMap (OSM) project. The rendering will happen on the OSM servers. Traffic heavy pages should consider the amount of requests to their servers and also consider contributing to the OSM project. (www.openstreetmap.org)
The map data it self is filed under the terms of the Creative Commons Attribution-ShareAlike 2.0 license. (http://creativecommons.org/licenses/by-sa/2.0/)