DigitalGlobe (digitalglobe.com) is a satellite imagery company. They have provided imagery to HOT initiatives in the past, and are currently working with Mapbox on providing more imagery to OpenStreetMap. April 2014 announcements:
- digitalglobeblog.com 'Mapping the World with OpenStreetMap via Mapbox'
- Mapbox blog 'New imagery for OpenStreetMap'
It may be that Bing imagery is also sourced from DigitalGlobe in some parts of the world.
Using DigitalGlobe imagery in editors
The easiest way to do this now is probably to use "Mapbox Satellite" available as a simple option within iD and JOSM. In the past we've had access to specific small areas via WMS servers more directly from DigitalGlobe.
You are allowed to trace data into OpenStreetMap based on Mapbox imagery. This permission is very explicit in the Mapbox Terms of Service, and this is also explicitly linked from their blog post relating to DigitalGlobe imagery . Vector data contributed to OpenStreetMap is then released under the OpenStreetMap License.
No legal issues, but there can be other issues around Using Imagery to be aware of.