As a quick update to anyone still looking for this info....
If you have firmware between 1.5x and 1.6, you should downgrade to 1.5 so you can use PSPKick and all the other wonderful homebrew out there.
Don't want to lose all the 'cool' features of your firmware? Then use a program called "Devhook" once you ahve downgraded. This basically lets you emulate any firmware you want (up to 1.71 as of this writing) flawlessly and be able to go back to 1.5 at the drop of a power switch. VERY useful.