yahoo mail fail
Despite promising to restore Yahoo Mail service to its customers by 5pm EST, an unknown number of users are still unable to log in, and remain without email service.

An unknown number of users have been affected by Yahoo's as-yet-unnamed problem, spanning at least two and a half weeks - a problem that was not openly acknowledged by Yahoo until yesterday.
Only today Yahoo Mail's head Jeff Bonforte finally addressed the massive outage that has kept Mail users from sending or receiving email since at least November 25, in a blog post on the Yahoo Mail Tumblr.
As of this writing, Bonforte - the man who told employees at a staff meeting last Friday that the only way Yahoo Mail customers would leave the service was if Yahoo kicked Mail users in the [testicles] - is on Twitter hurrying to politely placate Mail's outraged users.
No access since Monday; mail missing since November 25
Mr. Bonforte wrote on the Yahoo Mail Blog that the outage is related to a "hardware problem" at one of the company's mail data centers, and that users lost access around 10:30 p.m. PT Monday night.
Yahoo did not acknowledge the problem until Tuesday, doing so on Twitter.

Yahoo's Help page clarifies that an unknown number of users are missing and have been unable to send or receive mail since November 25.

This is only slightly better than the way Yahoo eventually responded to its users over the enormous public failure of its Mail redesign back in October (the second redesign within a year, Marissa Mayer's forced Gmail cloning experiment).