I'm getting "Cannot open /media/.hal-mtab" while trying to "safely remove" flash drive. Any solution?

Well, after some research, googling, walking here and there I've got the result. Flash drives are u/mounting properly, but I don't know exactly what did the trick.
All my moves were semi chaotic - At 1st, I've uninstalled autofs package (can anybody tell me what is it actually for?). 2nd - I've commented flash mount point in fstab. And 3rd - I've installed a package named pmount (also interested what is it for? Is it necessary to have been installed?)

I think the problem was the uncommented fstab entry (which you said you now commented). If you have an uncommented fstab entry, it is ignoring HAL and is being manually mounted and not automounted. pmount is another automounting tool used via the command-line. It works with WMs/DEs that do not natively support automounting via HAL. You can safely get rid of pmount if you're using KDE, but you should probably reinstall autofs (not entirely sure what this does, but I have it on my system [it's installed by default I believe] and it looks like it's involved in automounting).

now I have cdrom and flash UNcommented. All works fine. One detail - flash must be mounted to /media/sda1 but not to /mnt/flash that was before it.

/dev/sda1 /media/sda1 vfat rw,dmask=0000,fmask=0111,users 1 0
/dev/cdrom /mnt/cdrom auto noauto,user,ro 0 0