For what it's worth, it was just posted to the University of Waterloo CS announcement list:

"I just received news that John McCarthy passed away in his sleep a few hours ago; he was at home."

Do you have a source (i.e. link to the mailing list)? Unfortunately the person who added it to the Wiki article didn't add one.

The archives to the mailing list are private, so I can't link. You can see in the wikipedia history that who ever made the edit claims to have received word from McCarthy's sister.

Yeh; unfortunately that's not a strong enough source, particularly for this sort of edit :)

Thanks anyway - I am sure it will appear in time.

Usually stuff like this is legit; but sometimes it isn't. So the policy is to have a reliable source or nothing.

I tweeted at @stanfordeng, hoping that they can confirm.