Mrbrown from
ps2dev has released PSPSDK 1.0+beta. This will make coding and compiling for the PSP much easier. The PSP Software Development Kit (PSPSDK) is a collection of Open Source tools and libraries written for Sony's Playstation Portable (PSP) gaming console. It also includes documentation and other resources developers can use to write software for the PSP. PSPSDK is distributed under a BSD-compatible license. See the LICENSE file for more information.
Get the PSP SDK
HEREGet the toolchain (needed for the PSP SDK)
HERE