When configuring a 2.6.x Linux kernel for an iBook, remeber to disable (or compile as a module) "i8042 PC Keyboard controller" and "8250/16550 and compatible serial support" otherwise you will get lots of "IN from bad port 64 at ..." (this is because the dmesg buffer overflows with an error; this error is caused by your .config having a bogus ISA driver) and your ibook will hang while trying to sleep.
Device Drivers --->
Input device support --->
< > i8042 PC Keyboard controller
Character devices --->
Serial drivers --->
< > 8250/16550 and compatible serial support