How many distro package maintainers work for any given OEM? I think the most effective system (setting aside cost factors) would be for OEMs to do their own QA and contract out the adjustments. The internal QA is good, because it gives tech support access to people with experience on the quirks of the system, but there's a huge benefit to contracting out the adjustments to the distro, since there's a good chance that you'll benefit from the results of somebody else contracting out similar adjustments. And you also benefit from having the changes go upstream; that is, if you install Ubuntu Hardy on your netbook and tweak it until it works nicely, that'll get good results until your customers decide to install Jaunty on it and have no idea how to make the trackpad feel right. If you pay Ubuntu to detect your trackpad and use defaults that make it nice to use, this carries over to people installing Jaunty or, if those defaults get into upstream projects, even Gentoo.