I too have the problem of automount of USB memory sticks not working (in Kubuntu Hardy Heron 8.04).  Here is my dmesg output when I insert *two* of them:

[27635.515591] usb 3-1: configuration #1 chosen from 1 choice
[27635.525787] scsi3 : SCSI emulation for USB Mass Storage devices
[27635.536866] usb-storage: device found at 4
[27635.536876] usb-storage: waiting for device to settle before scanning
[27640.536200] usb-storage: device scan complete
[27640.537919] scsi 3:0:0:0: Direct-Access     Kingston DataTraveler 2.0 1.00 PQ: 0 ANSI: 2
[27640.551574] sd 3:0:0:0: [sdb] 7902208 512-byte hardware sectors (4046 MB)
[27640.552261] sd 3:0:0:0: [sdb] Write Protect is off
[27640.552268] sd 3:0:0:0: [sdb] Mode Sense: 23 00 00 00
[27640.552273] sd 3:0:0:0: [sdb] Assuming drive cache: write through
[27640.555130] sd 3:0:0:0: [sdb] 7902208 512-byte hardware sectors (4046 MB)
[27640.555774] sd 3:0:0:0: [sdb] Write Protect is off
[27640.555781] sd 3:0:0:0: [sdb] Mode Sense: 23 00 00 00
[27640.555786] sd 3:0:0:0: [sdb] Assuming drive cache: write through
[27640.555798]  sdb: sdb1
[27640.712763] sd 3:0:0:0: [sdb] Attached SCSI removable disk
[27640.712863] sd 3:0:0:0: Attached scsi generic sg1 type 0
[27644.192822] usb 1-4: USB disconnect, address 3
[27645.578523] usb 1-4: new low speed USB device using ohci_hcd and address 4
[27645.785812] usb 1-4: configuration #1 chosen from 1 choice
[27645.795006] input: Topro USB Mouse as /devices/pci0000:00/0000:00:13.0/usb1/1-4/1-4:1.0/input/input11
[27645.822568] input,hidraw0: USB HID v1.10 Mouse [Topro USB Mouse] on usb-0000:00:13.0-4
[27645.950002] usb 1-4: USB disconnect, address 4
[27646.802252] usb 1-4: new low speed USB device using ohci_hcd and address 5
[27647.009616] usb 1-4: configuration #1 chosen from 1 choice
[27647.018799] input: Topro USB Mouse as /devices/pci0000:00/0000:00:13.0/usb1/1-4/1-4:1.0/input/input12
[27647.046297] input,hidraw0: USB HID v1.10 Mouse [Topro USB Mouse] on usb-0000:00:13.0-4
[27647.286156] usb 3-5: new high speed USB device using ehci_hcd and address 7
[27647.430997] usb 3-5: configuration #1 chosen from 1 choice
[27647.445013] scsi4 : SCSI emulation for USB Mass Storage devices
[27647.450448] usb-storage: device found at 7
[27647.450458] usb-storage: waiting for device to settle before scanning
[27647.589236] usb 1-4: USB disconnect, address 5
[27649.529689] usb 1-4: new low speed USB device using ohci_hcd and address 7
[27649.736999] usb 1-4: configuration #1 chosen from 1 choice
[27649.746207] input: Topro USB Mouse as /devices/pci0000:00/0000:00:13.0/usb1/1-4/1-4:1.0/input/input13
[27649.773732] input,hidraw0: USB HID v1.10 Mouse [Topro USB Mouse] on usb-0000:00:13.0-4
[27652.449843] usb-storage: device scan complete
[27652.451333] scsi 4:0:0:0: Direct-Access     Generic  STORAGE DEVICE   1033 PQ: 0 ANSI: 0
[27652.465083] sd 4:0:0:0: [sdc] 512000 512-byte hardware sectors (262 MB)
[27652.466662] sd 4:0:0:0: [sdc] Write Protect is off
[27652.466668] sd 4:0:0:0: [sdc] Mode Sense: 02 00 00 00
[27652.466674] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[27652.469423] sd 4:0:0:0: [sdc] 512000 512-byte hardware sectors (262 MB)
[27652.470912] sd 4:0:0:0: [sdc] Write Protect is off
[27652.470918] sd 4:0:0:0: [sdc] Mode Sense: 02 00 00 00
[27652.470923] sd 4:0:0:0: [sdc] Assuming drive cache: write through
[27652.470935]  sdc: sdc1
[27652.472315] sd 4:0:0:0: [sdc] Attached SCSI removable disk
[27652.472403] sd 4:0:0:0: Attached scsi generic sg2 type 0

In fact, I can mount each of them explicitly with something like:
  mount /dev/sdc1 /media/usb1
so the problem lies purely in the automount.