Just for clarification, yes, this is fairly equivalent to Gamers Day here in the US in that SCEI actually starts cranking up dem dere hype wagons, though I don't think the scale is anywhere near as equal to what's happening this and last year here locally.
What's interesting is that of course this year is the Kaz Parade for the first time, and I wouldn't doubt in the least that the so-called "momentum" that the PS3 has right now is due in no small part to the machinations of one Mr. Hirai. I don't think Sony expected to perform like they did vs. other systems this early into the year, but I've little doubt that they've whipped up a fairly steady string of reveals going into at least the middle of this year.
I know for a fact that Gamers Day is going to have some serious shit with which the US 1st party departments will throw down (historically 2nd and 3rd parties dig having the platform to do the same), and then of course there's E3. Then there's Games Convention as that's become the Euro-centric base for stuff. That's a few solid months of talking about stuff that will hit this year, yes, but also reveals of what's to come in '09.
If there's one thing Sony is good at, it's baiting people with teases of what's to come. It's one of the main areas where the competition could learn a little, though of course one runs the risk of CG trailergate a la E3 '05. Needless to say, though, Sony hasn't been sitting around; they've got a TON of stuff to show off for the rest of the year and into the next.
Any good PR plan staggers these announcements throughout the early part of the year to build hype while other companies sprinkle their respective announcements into the mix to create pockets of interest. I can honestly say we haven't seen the least of what Sony has planned for upcoming releases yet by any realistic measure. There's still lots o' fun stuff to come, and I'm pretty sure this is going to be a fairly major stop along the hype train.