The news published by Yahoo Japan, allegedly comes from the exchange's bankruptcy lawyer who suggests the bitcoins were found on 7th March in a wallet used by MT. Gox prior to June 2011. The 200,000 bitcoin would equate to just over 23% of the entirely funds presumed lost by the company in the wake of widespread theft that is said to have occurred on the exchanges for a period of several years. Given the date, these funds may be separate from that money, however.
Though the release does mention that the funds were found, it does not clarify as to whether the Mt. Gox still has access to any bitcoins inside.