To the shock of very few, the advertisement about a week ago listing a “PSP-4000” in addition to PSPs 1000 through 3000, and the Go, has been disowned by the advertiser, who calls it an error.
https://lastchance.cc/some-advertisement-mentions-psp-4000-5430044%3C/a%3E%3C/p%3E
Negative Gamer adds that Sony’s response to the issue remains the standard no-comment for rumor and speculation, but I can’t say that policy indicates anything other than what this is, an advertiser mistake.
PSP-4000 Advert was ‘Mistake’ [Negative Gamer]