Sony uses a proprietary i/o control interface for it's function keys, scroll wheels, acpi, and screen control.
sonypid handles some of these.
spicctrl is the user space control utility.
sonypid is built into most linux kernels from 2.4.7 on up. You may or may not have to config your kernel to enable it, many (such as Suse 8.2) already have it enabled out of the box, so then all you need is the spicctrl util.
With it I now can control my screen brightness and get readings on the battery/power situation.
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Here are the links I used (works for most vaios):
<li><a href="http://www.shallowsky.com/vaiotricks.html">Sutpid Vaio Tricks (on Linux)</a></li>
<li><A href="http://spop.free.fr/sonypi/">Sony programmable I/O Control device</a></li>