Stick a fork in it, this beta's almost done. Konami have just issued a statement on the Metal Gear Online site, which reads:
...we regret to inform you that due to extraordinary levels of traffic from all around the globe, we have been unable to run the service to the level we expected. As a temporary measure, we will be deferring the start of the US public beta test until we are able to stabilise our server. We would like to apologise for all inconveniences as well as confusion caused.
As a result, the beta's start date - which was meant to be today - has been postponed, with an announcement on a new date expected on Tuesday (Europe: "we will be suspending the European public beta test and restart it once we stabilise our server"). To compensate for this, the beta will be run for another week, and is now due to end on the 11th of May, rather than the 6th. Good thing Konami are doing all this now, such a loooooong time before the game's due for release, because if they left it to the last minute (like, a month and a half before release, say), people might start to worry!
[Metal Gear Online]