It's rare that I think of a solution to a perl problem that DOESN'T involve regexes, hashes, or odd data structures:

#!/usr/bin/perl -w

use strict;

my @array=('bent','svend','gert','pete','svend','pete');
my $prev="";
my $count=0;

foreach(sort @array) {
    if($prev ne $_) {
        if($count) {
            printf("%s:%d ",$prev,$count);
        }
        $prev=$_;
        $count=0;
    }
    $count++;
}
printf("%s:%d\n",$prev,$count) if $count;
[download]

Obviously, it could be golfed down somewhat, but I wanted to go for the clearer version.

The output isn't in the exact order that RuneK specified, but I'm not sure if that's important or not.
--
Mike