Does the Apple keyboard require 8 digits to pair, or could i pair with, say, 4 digits, as the usual cell phones and other Bluetooth device ?
It really depends on the BT software on the desktop. For example, when I pair my Windows machine with my Apple BT alu-keyboard, it requires 6 characters, not 8.
I've heard of people pairing it with BT Nokia cellphones, WM devices, etc - so it should not be a problem or a limitation set by Apple AFAIK.
If pairing with a Mac OS X system, yeah, it's 8 digits.
It has been found that the Apple keyboard can work with different number of digits. The issue is that until an Apple keyboard is somehow initialized by a MAC and given an identity, it cannot remain connected under linux. I do not know whether this a Linux Issue, or this is an unnamed keyboard issue, but since the keyboard was given a name under MacOSX, it connects fine under Windows and Linux.