It's Sony Pictures Entertainment that got hacked, not Sony. They're completely separate companies, yet the media fails to recognize that. Very annoying and confusing, it's almost deliberately.
Sony is a very large conglomerate: while it would be incorrect to say that, say, Sony Computer Entertainment (the subsidiary that runs Sony's video games operations) got hacked, Sony Pictures Entertainment is a wholly-owned subsidiary of Sony Entertainment, Inc., which is itself a wholly-owned subsidiary of Sony Corporation.[1] It's as much "Sony" as any of its other subsidiaries.
[1]: http://www.sonypictures.com/corp/aboutsonypictures.html
Sony -- Script to Screen: http://youtu.be/4P4Wl1Ogg_g
http://www.theregister.co.uk/2014/12/03/strange_things_afoot...