Quoting Thomas Bächler <thomas@archlinux.org>:
- xfce4 battery meter seems broken (please confirm)
Why only xfce? If only one user reported that, I guess it is an ACPI problem on this machine that is not xfce-specific, but rather machine-specific (and the reporter happens to use xfce). Due to the heavy ACPI changes in this release, this seems likely.
My best guess is the following: Problems in 2.6.20 were related to the fact that acpi modules firstly were not loaded by default for most of the users. Hence, no directory /proc/acpi/bat existed. The xfce4-battery-plugin resolves the issue by showing that 50% thingy.
From the release logs, IIRC, as of 2.6.21 the acpi stuff moves now from /proc/acpi to /sys. This is supposed to be work in progress, but the battery stuff might be already affected. (I'm fishing here, I didn't check the patches)
-T