When you say failed I presume you mean it printed choked. Here is the same script as a command line utility. Run it on the server that choked. As root, and as nobody/apache.

#!/usr/bin/perl
my $host = gethostbyname($ARGV[0]);
print $host ? "Got host $host\n" : "Choked!";
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It fails because gethostbyname() is failing. Some systems do have a crap gethostbyname(). In fact freebsd (which I see is what you are using) is one such OS. Do a google for 'gethostbyname freebsd perl issue' or some such. From memory the gethostbyname function is not thread safe up until the most recent of the freebsd releases.

So.....

• Freebsd has known issues with gethostbyname. I use Linux so don't know the details but there may be a patch for the core function.
• You have now effectively isolated the bug to gethostbyname() failing under some circumstances and have a test case.
• You are using 5.8.0 which was by all reports less than optimal. I would strongly consider recomiling perl using 5.8.3. I seem to remember there is the option to not use the systems native gethostbyname() - something like 'system has broken gethostbyname()' so let perl know.
• Getting 5.8.3, compiling, installing it into the default location (/usr/local/lib/perl5/5.8.3) will not overwrite anything and will probably be the quickest fix if it works. It will take about 15 minutes or so to do.

You may need to install libwwwperl (if you do not include the old 5.8.0 lib and site/lib into @INC during the configure. Anyway if you do it is just /usr/local/bin/perl5.8.3 Makefile.PL && make && make test && make install. This forces linking to 5.8.3 and installation into the 5.8.3 tree. Once it is in all you need to do to the test case is put #!/usr/local/bin/perl5.8.3 to run the test case against the new perl. If it works you have a cure. I would then just remove/rename the /usr/bin/perl (probably a symlink) and link it to the new 5.8.3 binary. You can always undo the link if random stuff happens (like none of the 5.8.0 modules can get found as the lib paths were not compiled into your new perl)