Err, by that line of thinking, Google leveraged Linux (the hard work of volunteers) to earn tens of billions and does not release the modified code for use of the volunteers. Of course they are not required to, but it isn't fair to Linux developers who have worked their butts off to develop Linux.
>It's more like Linus say you can't use the code, but Google use them anyway.
By installing the Bing Toolbar, users are giving permission to track their clicks. If Bing's server farm is searching Google and parsing the results then it is more like your example.
They employ Andrew Morton and Ted T'so, and have been working pretty hard to get the delta between their custom Linux and upstream down- I'd say they've been pretty fair to Linux developers.