So it seems Sony have included an ISO loader in their newest firmwares, something to do with downloading games perhaps. No help to any of us at the moment, but it's there! Who knows what it could mean.
Good news is that DarkAlex plans to incorporate it into 3.51 OE.

Mathieulh has explained on the Devsgen PSP forums that Sony has included an official ISO loader in PSP firmware versions 3.50 and 3.51. The loader is called np9660.prx and will apparently let PSP users load ISO files off their memory sticks.

The first explanation that comes to mind regarding the official ISO loader is that Sony is planning to release downloadable PSP titles either through PSN or a similar service geared exclusively for the PSP. The company has already mentioned earlier this year that a download service for the PSP is in the works.

French PSP news site PSP-Generation also notes that Dark AleX and Mathieulh will be patching the np9660.prx file for use in custom firmware 3.51 OE.

Ville_Valo via pspupdates.qj.net »