Gameshark has created the first "custom" firmware package that has all the abilities of a 1.50 PSP, but has the added media capabilities and codecs of 2.0+.

At the moment, you can only run this custom firmware using MPH's Firmware Launcher. Do not try to use this package as an actual upgrade. Here's what GameShark had to say:

Features
1.5 - Full HB
2.0 Media Fetures

This is a Beta If there are any problems Just Let me know

I hope to add 2.0 UMD support to the next release

Also next release will be pacaged so that it can be added to an existing 1.5

Right now you need The MPH FW Launcher