I can confirm this behavior on my laptop too with a clean install of Feisty. Here is what I posted in the ubuntu forums, with as much info as I have figured out:

I have looked through the ubuntu forums and kubuntu forums and have found problems that are close to the same but not quite. So I have decided to start a new thread and hope it helps.

The Problem: In Kubuntu Feisty clean install my USB LaCie 160GB HD is not automounted, nor can a regular user mount it with ntfs-3g. I have install ntfs-3g and ntfs-config. I set both internal and external drives to be writeable. My WinXP partition mounts with ntfs-3g fine and dandy using fstab.

More Symptoms: Once plugged in a window pops up asking if I wish to open the folder or what not. I can try any of the options and the window goes away but the disk is not mounted. So I can then go into konqueror and to the Services tab on the side. I can click on the USB disk that shows up under Storage Media. I can click on it and I receive:

(Window Title: Error - Konqueror)
hal-storage-removable-mount-all-options refused uid 1000

If I try instead to right click on the drive and click mount I receive:
(Window Title: Error - kio_media_mounthelper)
hal-storage-removable-mount-all-options refused uid 1000

Next I tried using pmount-hal:

pmount-hal /dev/sdb1

and get this spit out:

libhal-storage.c 1401 : INFO: called LIBHAL_FREE_DBUS_ERROR but dbusError was not set.
process 9726: Applications must not close shared connections - see dbus_connection_close() docs. This is a bug in the application.

And I have read access but not write access. A glance at mtab reveals (last two lines):

/dev/disk/by-uuid/04F8E5B6F8E5A5E0 /media/winXP fuseblk rw,nosuid,nodev,noatime,allow_other,blksize=4096 0 0
/dev/sdb1 /media/Arrowboxed ntfs rw,noexec,nosuid,nodev,uid=1000,gid=1000,umask=077,iocharset=utf8 0 0

Here the first line is my internal WinXP partition and the second line is my external HD. And it looks like the filesystem for my XP partition is fuseblk, and ntfs for the USB HD. So the next idea is to use the -t option in pmount to specify I want to use ntfs-3g. And I use:

pmount-hal /dev/sdb1 -t ntfs-3g

And this results in:

libhal-storage.c 1401 : INFO: called LIBHAL_FREE_DBUS_ERROR but dbusError was not set.
process 9811: Applications must not close shared connections - see dbus_connection_close() docs. This is a bug in the application.
Error: invalid file system name 'ntfs-3g'
Error: could not execute pmount

And indeed it does not mount. So I figure okay, lets try just mount:

sudo mount /dev/sdb1 /media/sdb1

And it is mounted with read access only for root only. And again mtab has:

/dev/disk/by-uuid/04F8E5B6F8E5A5E0 /media/winXP fuseblk rw,nosuid,nodev,noatime,allow_other,blksize=4096 0 0
/dev/sdb1 /media/sdb1 ntfs rw 0 0

Which appears to mean that it is mounted with the old ntfs driver. So it's back to unmounting and trying to specify ntfs-3g with mount:

sudo mount -t ntfs-3g /dev/sdb1 /media/sdb1

And the HD is now mounted with read and write for everyone. And mtab reads:

/dev/disk/by-uuid/04F8E5B6F8E5A5E0 /media/winXP fuseblk rw,nosuid,nodev,noatime,allow_other,blksize=4096 0 0
/dev/sdb1 /media/sdb1 fuseblk rw,nosuid,nodev,noatime,allow_other,blksize=4096 0 0

And now we have both the internal and external using fuseblk. So in my limited knowledge it seems that maybe hal isn't recognizing the drive as ntfs-3g when I try to use pmount. I opened up kde-hal-device-manager and navigate to the external HD and under the advanced tab I see it has the property

volume.fstype       strlist      ntfs-3g

The property was checked while the device was unmounted so I don't think it was dependent on me mounting it as ntfs-3g. And now we are at the end of my skillset. It seems that some part is broken in how the drive is automounted. I have no idea what though. And assuming kubuntu uses pmount to automount usb devices it seems, to me at least, that something is not configured right with it. As a final note when I plug in my ipod it mounts fine, but it is formatted in fat32 and uses vfat to mount it according to kde-hal-device-manager and mtab. So please help me out if you can. I don't know what else to do. I do understand that I could add a line to fstab, but I am plugging and unplugging the drive quite often. And I think it is important to try to track down what is actually wrong, not just avoid the problem.