Would it be possible to make a 2.60 Homebrew Edition? And flash it? If so, there would be no need for cracking the digital sig! It would be sort of like genetic engineering to create it:

Find the patch in 1.51 that blocks homebrew (check file sizes to do this)

Grab the unpatched one from the 1.50 firmware

Transplant it into a 2.60 dump

Flash it

Maybe we could even find that homebrew "gene" and use the TIFF exploit to patch our PSP's so there would be no need for the EBOOT Loader on 2.00!