I recently bought a Clevo P170EM with a hybrid Intel HD 4000/Radeon 7970M setup. The Intel card was supported perfectly in Linux out of the box. Getting support for the 7970M took a few months, but the most recent Catalyst release supports it under Ubuntu 12.04, and setup was relatively painless. The only minor hassle of this setup is the need to restart the X server to switch the active card. I understand 12.10 is a little dicier due to the new version of X, and I don't know about any other distros, but I've been running this setup for a few months now without any problems and can highly recommend it. If the P170EM is too big, the P150EM is essentially the same hardware with a smaller screen. Every other hardware component except the fingerprint reader works perfectly in Ubuntu as well.
System76 also sells machines with Ubuntu pre-installed, and they recently introduced a model with discrete graphics, so you could also look into either their computers or the Clevo computers upon which their models are based (I believe the Bonobo, their discrete-graphicsed model, is based on the P370EM).