Konami has announced that the public beta for Metal Gear Solid Online is set to open up on April 21. The beta is expected to run for roughly fourteen days and will be made available to everyone who pre-orders Metal Gear Solid 4 at any major retailor. Upon pre-ordering, customers will be given a Limited Edition DVD that will also happen to contain a download code within it.
Apparently, they may also open the beta up for people who didn't pre-order as well, but that isn't a concrete decision as of yet. The pre-order program is expected to start in April, so you have a while to prepare for it.
Metal Gear Solid Online will feature 16-person multiplayer experience that is looking to deliver. With the online map information released today, it looks like this is shaping up to be a promising aspect for the franchise itself. We'll keep you up to date as more hits.