In deed some libs are not properly upgraded along with 'pcmanfm' but it's easy to work around:

lance@lance-desktop:~$ sudo apt-get install --reinstall pcmanfm
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libmtp8 xsltproc libegl1-mesa libntfs10 libegl1-mesa-drivers libevent-1.4-2
  libunity4 linux-headers-3.0-3 linux-headers-3.0.0-6-generic
  libdbusmenu-glib3 libindicate-gtk2 libgcr-3-0 libxcb-xfixes0 python-gconf
  libdbusmenu-gtk3-3 linux-headers-3.0-3-generic libgbm1 libgck0 python-webkit
  libdbusmenu-gtk3 gnome-doc-utils xdiagnose gir1.2-appindicator-0.1 tcl
  linux-headers-3.0.0-6 libnl1 liborbit2 libopenvg1-mesa intel-gpu-tools
  libntfs-3g80
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
  libfm-data libfm-gtk-data libfm-gtk1 libfm1
The following packages will be REMOVED:
  libfm-gtk0 libfm0
The following NEW packages will be installed:
  libfm-data libfm-gtk-data libfm-gtk1 libfm1
The following packages will be upgraded:
  pcmanfm
1 upgraded, 4 newly installed, 2 to remove and 0 not upgraded.
Need to get 560 kB of archives.
After this operation, 139 kB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe pcmanfm i386 0.9.9-0ubuntu1 [207 kB]
Get:2 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe libfm-data all 0.1.16-0ubuntu1 [139 kB]
Get:3 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe libfm1 i386 0.1.16-0ubuntu1 [76.2 kB]
Get:4 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe libfm-gtk-data i386 0.1.16-0ubuntu1 [16.9 kB]
Get:5 http://us.archive.ubuntu.com/ubuntu/ oneiric/universe libfm-gtk1 i386 0.1.16-0ubuntu1 [121 kB]
Fetched 560 kB in 3s (177 kB/s)     
(Reading database ... 180738 files and directories currently installed.)
Preparing to replace pcmanfm 0.9.8+git-6240436419-1~bzr459+p18~oneiric1 (using .../pcmanfm_0.9.9-0ubuntu1_i386.deb) ...
Unpacking replacement pcmanfm ...
Processing triggers for desktop-file-utils ...
Processing triggers for man-db ...
Processing triggers for menu ...
(Reading database ... 180739 files and directories currently installed.)
Removing libfm-gtk0 ...
Removing libfm0 ...
Processing triggers for desktop-file-utils ...
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
Processing triggers for shared-mime-info ...
Selecting previously deselected package libfm-data.
(Reading database ... 180658 files and directories currently installed.)
Unpacking libfm-data (from .../libfm-data_0.1.16-0ubuntu1_all.deb) ...
Selecting previously deselected package libfm1.
Unpacking libfm1 (from .../libfm1_0.1.16-0ubuntu1_i386.deb) ...
Selecting previously deselected package libfm-gtk-data.
Unpacking libfm-gtk-data (from .../libfm-gtk-data_0.1.16-0ubuntu1_i386.deb) ...
Selecting previously deselected package libfm-gtk1.
Unpacking libfm-gtk1 (from .../libfm-gtk1_0.1.16-0ubuntu1_i386.deb) ...
Processing triggers for shared-mime-info ...
Processing triggers for desktop-file-utils ...
Setting up libfm-data (0.1.16-0ubuntu1) ...
Setting up libfm1 (0.1.16-0ubuntu1) ...
Setting up libfm-gtk-data (0.1.16-0ubuntu1) ...
Setting up libfm-gtk1 (0.1.16-0ubuntu1) ...
Setting up pcmanfm (0.9.9-0ubuntu1) ...
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
Processing triggers for menu ...