it seems that Google Location Services is the location services provider for Firefox and Chrome. I have not been able to find any information about who is the location services provider for iOS and Mac's Safari browser. I don't want to just assume Google, although I'm guessing it probably is.
Does anyone know, and have a pointer to Apple's documentation on this? Most browsers have a privacy policy regarding location and I haven't been able to find this for Safari either. This page doesn't say who the provider is: http://support.apple.com/kb/HT1975, and neither does their privacy policy: http://www.apple.com/privacy/.
Apple.
They use crowd-sourced Wi-Fi/cell tower info database (probably shared with Skyhook as they have previously recommended people to update Skyhook if something is inaccurate).
GPS is GPS.
http://www.apple.com/pr/library/2011/04/27location_qa.html
Hope this helps.