Geomob was interesting tonight. A couple of notes (for my own purposes really):
The Domesdaymap taking the Domesday project and putting it into a useable searchable map was great - the amazing thing about it is that, despite being one of the most important European surveys in pre-modern times, it wasn't turned into open data until one person discovered an academic's Access database and decided to make it into a useable service with an API and a CC licence. Good work!
Nestoria talked about their switch from Google Maps to OpenStreetMap, a tale which has been admirably blogged elsewhere and made a big splash. Apparently they use and really like a rendering engine (client-side) called Leaflet. They decided not to make their own tiles in the end, but despite that they said that TileMill for making yr own maps was fab, and everyone could and should use it for making all sorts of maps. Also, MapBox has some beautiful map renderings to look at.
"Mental Maps": two design students did some work warping OpenStreetMap data to fit people's mental maps of places. They applied it to the tube map too, and made a really lovely print of the result.
MapQuest gave some interesting detail about their server setup. Interesting for map/data/sysadmin nerds I mean, of course. They use a very homogeneous cluster system: each node is capable of rendering tiles, or pre-rendering routing, or whatever, and they allocate jobs according to demand using a "distributed queue" system; standard CDNs aren't so useful because with OpenStreetMap you can't be sure in advance how long the tiles should be cached; oh, and MapQuest uses different rendering "styles" for US, UK, and mainland Europe (and so on), because people in those countries have different expectations about how the map should look.