There are various LEDs on the A110 with different meanings and support status.
The red battery LED is on when the battery is being charged.
If the battery charge drops below ca. 10%, the red battery LED starts blinking. This seems to be controlled at a very low level (as it works both in the BIOS screens and in Linux without special drivers, as far as we know) — either in the BIOS, ACPI, in a hardware circuit, or most likely in the embedded controller (EC) of the laptop.
Blue when switched on. Blinks blue when in suspend-to-RAM.
See Wireless for details. Using ndiswrapper it blinks when transferring data. Using native rtl8187 it just stays on.
Num lock LED
Works if NumLock active.
Caps lock LED
Works if CapsLock active.
Works as expected.