Well, I installed withed00r ios 5(ios 3.1.2) RC in my iPhone 3G and did work great. But DreamBoard, a better SpringBoard and alternative to WinterBoard, just makes your iphone go to Safe Mode after installation from Cydia. Even re-instalation, erase, Install again, still behaves like that. And it is the first thing I tried to install in a brand new and clean withed00r ios 5 RC installation...
If anyone else had tried DreamBoard using withed00r and had been sucessful, please share your experience, so we all can learn
So, I am planning to go back to ios 4.2.1, until the full whited00r ios 5 comes out or even red00r comes out, which would be based in ios 4, instead of ios 3, and may be that will ease some compatibility problems between apps and older iDevices.