After alot of thinking about this I've come to the conclusion that I agree that there should be autodetection of chipsets. I have been reading some pciset documents from Intel, and as Andrew says there is really only smaller differences (between the PCI chipsets that is). But all this depends on one things; if it is possible to, with 100% accuracy, determine what chipset the BIOS is running on. If this is possible, is see no reason not to include autodetection. A wild guess is that the code for the various chipsets (all together) is not more then a couple of kB.
Perhaps it's the best idea to make "chipset-addons", the end-user can choose the add-on and put it into the main-code, like in the Award- or AMI-Bios, modular.
A general Plugin-Interface with some Plugin-Types and a chipset interface. So openbios get's modular and has nearly infinite features, only limited to the amount of flash-memory. ;-)
Ciao, Stephan