But even the HBL for the PSP has been able to get kernel access in certain firmwares. If I remember correctly, there was even a ISO loader for one of them (don't feel like looking up which one, but I think it was 5.03). And I'm talking about the models with "un-hackable" MBs (i.e. the 3rd gen PSP-2000s and the 3000s). Also there is the new 6.20 loader that (supposedly) has kernel access and boots to the HBL.
While I would say that the PSP is most likely an easier device to get this kind of access. Any progress with hacking the PS3 is great news. If a HBL can be made to work on PS3s with 3.50 and above, it still means that "the scene" is active and making progress. Good luck to anyone that is helping the PS3 hacking community. Every little bit of working code/exploits helps!