I can confirm this works on a PSP3000 (03g) I have 2 Motherboards so I'd figured I'd try it and it does work also a few people on pspking.de can confirm it works also on PSP 3k's with 03g MB's, unsure about 04g's though and I'm not trying it on my 04g.
If you wish to uninstall the permanent HEN you must have left the vshorig.prx in the root of your MemoryStick.
[PSP-1000, 1g] x1 Quad-Booting: 6.60 PRO-B10, 6.60 M E, 5.00 M33-4, 1.50
[PSP-3000, 4g] x1 OFW: 6.35, PRO-B10 (HEN)
[PSVita] x0 Getting 1 Soon
[PS3 320GB, Slim] x1 OFW: 4.11