Comment 32 for bug 537763

To expand slightly on the details SKid(Sven) posted, here is some tests done using Ubuntu 10.04, with and without acpi_osi=Linux.

http://spreadsheets.google.com/ccc?key=0Ap2XdAnh9KHQdFB2VWdiRkxpT2N3QVpuNFQ2VEpMVUE&hl=en

It looks like when adding acpi_osi=Linux to the boot parameters, the results on Ubuntu 10.04 and 9.10 are basically the same (with the exception that the touchpad on/off buttons (both fn+f9 and the dedicated key) now work.