OpenStreetMap (http://openstreetmap.org/) is an editable map of the whole world, which is being built largely from scratch using GPS traces, and released with an open content license.
These mapping evenings are a series of mini mapping parties around London, aimed at increasing the OpenStreetMap coverage of these areas, and also giving London OSMers a regular meet-up. We'll be arriving in the area from different directions, and mapping from our own slice of the cake diagram (below), before finally meeting at a pub at around 7:30 -8:00 pm. (The White Horse near Shepherd's Bush)
We are also interested in meeting new people who want to find out more about OpenStreetMap. Feel free to come along! If you are new to mapping, but want to give it a try, you might perhaps get one of us to give a little mapping demonstration. You'll need to get in touch and arrange to meet us somewhere (e.g. at Shepherd's Bush Hammersmith & City line station) before we meet in the pub later. Alternatively read the Map Making Overview and just give it a go! Note that you don't need a GPS unit, although if you have one, this is a fun way to put it to good use. Either way, you'll want a print out of the area you're planning to map, since London already has many street layouts sketched in (without streetnames). Alternatively you're very welcome to just join us later in the pub.
Ideally people will arrive in the area early and get as much mapping done as possible e.g. arrive at 5:30 and map two or three different slices, but you also have the option to arrive later on e.g. 7p.m. and map one small slice... or just turn up for the pub!
Official Website: http://wiki.openstreetmap.org/index.php/London/Summer_2008_Mapping_Party_Marathon/2008-07-02
Added by Harry Wood on June 23, 2008