I believe with the Blu-Ray being REGION FREE(for US and JP) pretty much makes it clear that it will be a MULTI REGION LAUNCH. Also since 360 has pretty much failed with no competition in JP it is pretty clear sony wants to hit a hard blow to MS and then REV will hit another, basically killing 360 in JP like they did with Xbox 1.
I believe SONY worries more about what the xbox 360 does in the USA, so that being said THEY WILL NOT give M$ a full year advantage, US folks actually get 360's unlike in JP, so expect PS3 in the US in MAY probably weeks after E3.
I see it like this
PS3 IN JP THIS APRIL and IN MAY IN THE US, Then even more shipments will roll out slowly and then a big shipment for the holidays for both US & JP, EU however gets it last in JAN 07.