With timing that only a British Government department is possibly capable of, the Ordnance Survey released their free data on April Fool's Day: a couple of days earlier and they could have hit March 2010's much more appropriate Blue Moon.

The data downloads can be found at: http://data.gov.uk/data/publicbody/Ordnance%2520Survey and consist of: 

• 1:250K Colour Raster
• 1:50K Gazetteer
• Boundary-Line
• Land-Form PANORAMA  ("mid scale" topographic/height vector)
• Meridian 2
• MiniScale
• OS StreetView (street level 1:10K rasters)
• Strategi  (vectors derived from 1:250K)

This is a big step for the Ordnance Survey who have a long history of charging what are considered high fees or severely limiting their 'free' products. There are many opinions as to how this will affect the UK's geospatial industry, ranging from "it will kick start a new map renaissance" through to "it will destroy the high quality and innovation that the Ordnance Survey is currently known for". Time will tell as to which opinion is closer to the mark...