There is also some controversy around it : the big players do data mixing from different sources, which is not strictly compliant with OSM licenses. Also some say that their bulk editing creates nice map data, but harms local potential mapping communities, with early case of Netherlands where AND contributed map data resulted to no real manual map updates afterwards. So some say that community, not map must come first, so the “guerilla mapping” is bad.
I'm aware of MS's generated US building footprints[0] but this hasn't (yet) been integrated into OSM (largely I think due to quality and bulk-import etiquette worries). And also StreetSide[1] but this isn't imported into OSM itself, rather it's displayed as an aid for editors.
Facebook is looking at contributions similar to MS's US building footprints (but for roads), but again this is mainly around tooling and generation rather than data sources, and is speculative as far as I've seen.
