The PlayStation Premiere - Sony Japan's own mini-E3.
After E3's downsizing in late '06, Sony decided to split up their big announcements for 2007. Since they no longer had the king of all trade shows via which they could show off their products to the world, they decided to show off their advancements in hardware (big firmware updates, price drops) and more western centric titles (the epic Killzone 2 unveiling) at E307 from July 11-13, and then show off their Japanese centric titles at their own private event in Japan on July 17th - the PlayStation Premiere.
Last year, the PlayStation Premiere came at us right out of left field. Just days after a lackluster E3 that contained little more than Killzone 2 and an InFamous teaser, sites across the web started reporting on a hefty number of PlayStation titles being announced at a show in Japan. This was the first we ever heard the name "PlayStation Premiere," and the only knowledge of the event we had prior to this was a post from the mod Duckroll on NeoGAF saying that there would be a "big event" for Sony in Japan in just a few days.
Why is the PlayStation Premiere significant? Because last year they announced these titles at the show:
Disgaea 3
Dynasty Warriors 6
Gran Turismo 5 Prologue
Metal Gear Online
Nobi Nobi Boy
Valkyria Chronicles
And they also showed new FFXIII/Versus footage, an MGS4 gameplay demonstration, and they announced the CC:FFVII PSP bundle as well as new PSP colors for Japan.
Given how much they showed off at the event last year, and given the complete lack of Japanese titles at Sony's E3 press conference, I believe that there will be yet another PlayStation Premiere sometime soon, and that with it will come some very big announcements.
To read more about last year's PlayStation Premiere, take a look at 1UP's article about the event.
