New BIOS 0206A again
Intel released the driver for the Centrino “Intel Pro/Wireless LAN 2100” chipset under an open-source license at sourceforge.net.
Ycarus (Yannick Chabanois) was so nice to send me a (partly) fixed version of the DSDT (BIOS Version 0205A) with which the battery status can be queried. You can find the compiled version here and the source code here. Remember that some things still might _not_ work. To use the DSDT you have to patch your kernel with the “ACPI DSDT in initrd patch” from http://gaugusch.at/kernel.shtml, just follow the instructions on that page.
New BIOS, version 0205A. Will try it tomorrow.