This is no early April Fool's joke, Konami is serious about shutting down the Metal Gear Online service beginning June 12th. What's slightly odd is that the shutdown, according to Konami, was long overdue.
On the official Konami website [via Andria Sang], the announcement about the termination of service for Metal Gear Online is made plain and clear, indicating that the game -- originally bundled with the 2008 espionage action title, Metal Gear Solid 4: Guns of the Patriots -- was only planned to operate for an estimated three years, however, due to fan support Konami kept the service running for an extra year.
The game itself was an online PvP type of affair involving unique stealth elements to the typical run-and-gun shootouts. The game certainly wasn't for everyone and it certainly didn't cater itself to the infamously large Call of Duty audience, however MGO did have a dedicated niche crowd that helped support and keep the service operational.
In celebration of the service being terminated on June 12th, Konami will be hosting a number of special events for the game leading up to the official shutdown.
I don't know about anyone else but this is the main reason why MMOs and free-to-play games are a huge turnoff. After investing money, time and dedication to an online title a company will always retain the right to close up shop and leave its members high and dry. Unlike retail the online market doesn't leave its consumers with a playable copy of the game even after the servers shutdown. It's definitely an unfortunate scenario for hardcore fans of MGO.
You can read more about the official shutdown over at the Official Konami Website. Just make sure you bring a Babel fish with you or Google Translate.