(my $version) = (m|(v?[\d\.]{2,})|g)[-1];
(my $version) = (m|/(v?[\d\.]{2,})|g)[-1];

##</code><code>##

#!/usr/bin/perl -w
use strict;

my @paths = qw (
'/tool/a/r/V2/V2DepCheck/1109.2.1/V2DepCheck.pm'
'/tool/a/r/p4/r/main/V2/V2DepCheck/169441/V2DepCheck.pm'
'/tool/a/r/p4/r/branches/bd32b/V2/V2DepCheck/175507/V2DepCheck.pm'
'/home/me/cvs/V2/V2DepCheck.pm'
'/tool/a/r/boost/1.36.0'
'/tool/a/r/cadence/itk/itkvd/v007');

foreach  (@paths)
{
   chomp ;  #not need here, use if reading from file
   
   #(my $version) = (m|tool/a/r.*?/(v?[\d.]{2,}).*$|i);
   (my $version) = (m|/(v?[\d\.]{2,}).*?$|);
   defined($version)? print "$version\n" : print "undefined\n";
}

__END__
prints:
1109.2.1
169441
175507
undefined
1.36.0
v007