just to add to what paper said I baught a PSP Value pack today from target. They had like 20+ instock so i looked over them all findging, no letter A, but B on every single one. I think the manager thought I was crazy but i wasnt. I opened up the psp when i got home and yep you guessed it! Its a v1.51. I talked to a worker and he said they got this stock a fews days sgo.
Hopefully Team Xecuter, wab, and all other psp hacking groups find a way for us 1.51 and aboves!