Well, for those of you who would like to program the PS3 without messing around with Linux, I have now completed a demo app that runs directly under the hypervisor. I.e. no linux needed, not even kboot. Source and binaries included!
It demonstrates graphics rendering with the CPU (directly to DDR memory) and multibuffering, as well as some needed system management (set video mode, reboot etc.)
This little program shows how to write an "otheros" from scratch, demonstrating how to do things like display stuff on the screen and return to GameOS.
It can either be started from kboot, using the "demo.elf", or directly from GameOS by installing the "otheros.bld". Both contain the same code, oterhos.bld is simply a gzipped binary instead of an ELF.
The demo runs for about 45 seconds (slightly less on NTSC machines), and then exits to GameOS. The screen mode is either 576i or 480i, depending on the region of your PS3.