When you run perl -v does it print 
This is perl, v5.10.1 ...

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or 
This is perl, v5.8.5 ...

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Whichever version it is, the modules you install must match because perl versions 5.8 and 5.10 are not binary compatible, i.e. modules compiled with 5.8 will not work with 5.10 and vice versa (except for pure Perl modules that don't check the version of the perl executable and don't use features of the newer version changed from or not present in the earlier version).

If you have both versions of perl installed on the same system, they must each have independent @INC paths for their modules. That means you need to install module X twice, once for each version.

The PREFIX= parameter to Makefile.PL is intended for use when you do not have root privileges and must install modules somewhere other than the standard /usr/lib (or whatever default). It will not - as you've seen - enable you to put v5.10 modules in v5.8 directories.

By the way, your posts will be far more readable if you add <code> tags around things like commands and output. If said <code> is lengthy you should also use <readmore> tags. Example: 

[mdstest@mds-qa2] $ ls
Changes Daemon.pm Makefile.PL MANIFEST README t Proc-Daemon-0.03

[mdstest@mds-qa2] $ perl Makefile.PL PREFIX=/usr/lib/perl5/5.8.5/i386-
+linux-thread-multi
Checking if your kit is complete...
Looks good
Writing Makefile for Proc::Daemon
[mdstest@mds-qa2] $ make
cp Daemon.pm blib/lib/Proc/Daemon.pm
Manifying blib/man3/Proc::Daemon.3
[mdstest@mds-qa2] $ make test PERL_DL_NONLAZY=1
/usr/local/bin/perl "-MExtUtils::Command::MM" "-e" "test_harness(0, 'b
+lib/lib', 'blib/arch')" t/*.t
t/00modload.t ..... ok
t/01filecreate.t .. ok
All tests successful.
Files=2, Tests=2, 5 wallclock secs ( 0.01 usr 0.06 sys + 0.02 cusr 0.1
+7 csys = 0.26 CPU)
Result: PASS
[mdstest@mds-qa2] $ sudo make install
Appending installation info to /usr/lib/perl5/5.8.5/i386-linux-thread-
+multi/lib/perl5/5.10.1/i686-linux/perllocal.pod

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In reply to Re^3: removing paths permanantly from @INC and adding new ones by keszler
in thread removing paths permanantly from @INC and adding new ones by onkar

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