I think it will be a little higher. There are bundles and the game is much more hyped than the previous MGS games.
Furthermore the average PS3 owner is much more "harcore" than the average PS2 owner was. Therefore I think that a first week of 300.000 should be possible.
I don't think it will have good legs though. But ultimately it could do around 600.000 I think.
I think PS3 sales could be around 60.000 release week, but dropping quite fast to its base level of around 10.000. Something like 60.000 - 40.000 - 20.000 - 15.000.