Can Linux Support a PCI Expansion Chassis?

Snowfox asks: "Between having multiple network cards, video cards, SCSI controllers, audio, etc, I'm always hurting for expansion slots. Five or six just aren't enough for an everything box. Several companies offer PCI expansion chassis. I see these vendors on the show floor at Game Developers Conference and Siggraph every year, but the prices are high and none of the vendors can tell me whether these support Linux. Has anyone had any dealings with one of these units?"

"Magma has some sweet-looking units which even support 64-bit PCI, Mobility has some units which are far cheaper, and DigiDesign has a 7- and 14-slot unit as well. All three claim to be Plug-And-Play for Windows and Mac, but as on the show floor, none have responded to inquiries about Linux support or which chipset is used to bridge the busses.

I know that Linux supports PCI-PCI bridges which are on the motherboard, as are commonly used for on-board network, sound and drive controllers, but what about these external offerings?"