Hi, All.  For what it's worth, our systems appear to have two versions of lam-devel and lam-libs after upgrading from SL4.5 to SL4.8:

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[root@lnx100 ~]# rpm -qi lam-devel
Name        : lam-devel                    Relocations: (not relocatable)
Version     : 7.1.2                             Vendor: Scientific Linux
Release     : 8                             Build Date: Fri 04 May 2007 01:50:22 AM EDT
Install Date: Tue 21 Aug 2007 04:28:45 AM EDT      Build Host: yort.fnal.gov
Group       : Development/Libraries         Source RPM: lam-7.1.2-8.src.rpm
Size        : 5043907                          License: BSD
Signature   : DSA/SHA1, Tue 22 May 2007 04:47:48 PM EDT, Key ID 25dbef78a7048f8d
URL         : http://www.lam-mpi.org/
Summary     : Development files for LAM
Description :
Contains development headers and libraries for LAM
Name        : lam-devel                    Relocations: (not relocatable)
Version     : 7.1.2                             Vendor: Scientific Linux
Release     : 15.el4                        Build Date: Sat 26 Jul 2008 10:59:07 PM EDT
Install Date: Mon 04 Jan 2010 11:36:23 AM EST      Build Host: yort1.fnal.gov
Group       : Development/Libraries         Source RPM: lam-7.1.2-15.el4.src.rpm
Size        : 5376440                          License: BSD
Signature   : DSA/SHA1, Sat 26 Jul 2008 08:25:26 PM EDT, Key ID da6ad00882fd17b2
URL         : http://www.lam-mpi.org/
Summary     : Development files for LAM
Description :
Contains development headers and libraries for LAM
[root@lnx100 ~]# rpm -qi lam-libs
Name        : lam-libs                     Relocations: (not relocatable)
Version     : 7.1.2                             Vendor: Scientific Linux
Release     : 8                             Build Date: Fri 04 May 2007 01:50:22 AM EDT
Install Date: Tue 21 Aug 2007 04:28:29 AM EDT      Build Host: yort.fnal.gov
Group       : System/Libraries              Source RPM: lam-7.1.2-8.src.rpm
Size        : 1051049                          License: BSD
Signature   : DSA/SHA1, Tue 22 May 2007 04:47:48 PM EDT, Key ID 25dbef78a7048f8d
URL         : http://www.lam-mpi.org/
Summary     : Libraries for LAM
Description :
Runtime libraries for LAM
Name        : lam-libs                     Relocations: (not relocatable)
Version     : 7.1.2                             Vendor: Scientific Linux
Release     : 15.el4                        Build Date: Sat 26 Jul 2008 10:59:07 PM EDT
Install Date: Mon 04 Jan 2010 11:32:16 AM EST      Build Host: yort1.fnal.gov
Group       : System/Libraries              Source RPM: lam-7.1.2-15.el4.src.rpm
Size        : 2495001                          License: BSD
Signature   : DSA/SHA1, Sat 26 Jul 2008 08:25:27 PM EDT, Key ID da6ad00882fd17b2
URL         : http://www.lam-mpi.org/
Summary     : Libraries for LAM
Description :
Runtime libraries for LAM
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I am unable to remove the older packages via yum, and instead need to use "rpm -e --nopreun".
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[root@lnx100 ~]# yum remove lam-devel-7.1.2-8 lam-libs-7.1.2-8
Loading "kernel-module" plugin
Setting up Remove Process
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Package lam-devel.i386 2:7.1.2-8 set to be erased
---> Package lam-libs.i386 2:7.1.2-8 set to be erased
--> Running transaction check
Beginning Kernel Module Plugin
Finished Kernel Module Plugin

Dependencies Resolved

=============================================================================
 Package                 Arch       Version          Repository        Size 
=============================================================================
Removing:
 lam-devel               i386       2:7.1.2-8        installed         4.8 M
 lam-libs                i386       2:7.1.2-8        installed         1.0 M

Transaction Summary
=============================================================================
Install      0 Package(s)         
Update       0 Package(s)         
Remove       2 Package(s)         
Total download size: 0 
Is this ok [y/N]: y
Downloading Packages:
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
error: %preun(lam-libs-7.1.2-8.i386) scriptlet failed, exit status 2
error: %preun(lam-devel-7.1.2-8.i386) scriptlet failed, exit status 2

Removed: lam-devel.i386 2:7.1.2-8 lam-libs.i386 2:7.1.2-8
Complete!
[root@lnx100 ~]# rpm -qi lam-devel-7.1.2-8
Name        : lam-devel                    Relocations: (not relocatable)
Version     : 7.1.2                             Vendor: Scientific Linux
Release     : 8                             Build Date: Fri 04 May 2007 01:50:22 AM EDT
Install Date: Tue 21 Aug 2007 04:28:45 AM EDT      Build Host: yort.fnal.gov
Group       : Development/Libraries         Source RPM: lam-7.1.2-8.src.rpm
Size        : 5043907                          License: BSD
Signature   : DSA/SHA1, Tue 22 May 2007 04:47:48 PM EDT, Key ID 25dbef78a7048f8d
URL         : http://www.lam-mpi.org/
Summary     : Development files for LAM
Description :
Contains development headers and libraries for LAM
[root@lnx100 ~]# rpm -e --nopreun lam-devel-7.1.2-8 lam-libs-7.1.2-8
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Sincerely,
Devin