The announcement was silent on the BTC they still retain. I can't find any direct statements by anyone at Gox that all they have left is 2K. I'd be very grateful if someone could point it out if it exists.
The 2K BTC were mentioned on the leaked MtGox documents which were published one week ago or so. Given that many facts in those documents match with information that was published later on, it appears that those documents could be authentic.
See http://two-bit-idiot.tumblr.com/post/77988833128/the-final-g... for a link to the document and for more information.