I've noticed mounting USB-drives and USB-sticks with "noatime" boosts writing big files to them even by 50-80 % (measured with clock). I am very familiar with udev rules, too.

What I want to do, is not to create an udev rule for any specific drive or stick (I know how to do this), but to cause the Linux kernel to ALWAYS mount ANY USB or FireWire drive with certain options, in this case "noatime".

This includes automatic (KDE, GNOME, etc.) and also manual mounting - I tend to forget to specify "-o noatime" when I issue the "mount" command and while I can of course "mount -o remount,noatime" while it's copying, it tends to freeze and in the end I either have to abort the copying operation or wait for ages. One way coming to my mind is aliasing "mount" with "mount -o noatime", but I fear this might cause issues in the system. I also prefer to use autofs only for network drives (NFS).

Where could I specify "noatime" as the default option for all removable devices?

For gnome, theres a couple of options: in gconf-editor /system/storage/default_options, you can add filesystems and put the noatime option onto every one of those (you really only need ntfs, vfat, ext*).

Gnome uses gnome-mount to do its actual mounting. Hacking the source to include noatime into the mount flags is very easy too, but slightly more advanced.

If you want to be even more advanced, you can hack the kernel. The relevant file is fs/namespace.c around line 1927, you can change that to allow noatime permanently for all calls to mount. This option might seem radical, but Ive been using this since 2.20 kernels with no issues whatsoever.

As for KDE, I am not too sure. I believe kde 3.5 uses HAL, but KDE4 dont know.