I actually tried the same code on other distros (Ubuntu with Intel GPU and Gentoo with ATI GPU), my scene was rendered fine there.
Only on the first one (Fedora 12, Nvidia Quadro FX580, proprietary drivers), that I had the problem. Is there any known distro/graphics card specific issues? Thanks again!
This code looks fine to me.
Someone else had this exact same problem, and the issue turned out to be that glClear(...) was being called every time an object was drawn--just in case, have you done anything of that sort in your source?