so yahoo claim they got the "request" and LEGALLY had to grant that access, while google, MS, facebook, working in exactly the same legal environment say:
We've never received such a request, but if we did, our response would be simple: 'No way.'
"Facebook has never received a request like the one described in these news reports from any government, and if we did we would fight it."
MS and Twitter - nosir, not us!
So who's the naughty boy here? Yahoo says: we had to comply with the law. Google says: we wouldn't comply with the law. Facebook say: we would fight the law.
And it's quite embarrassing that they lie about "never getting such a request", it's just silly. If NSA went to milk yahoo, it would have DEFINITELY gone to get the same AND MORE from google, facebook, MS and twitter, why wouldn't they?