I'll agree with your definition of "hack", with a side comment. Perl is such a rich language that I am learning new features every time I start a project. Because of that, yesterday's "wonderfully clean code" becomes today's "childish hack".

For example: I've recently gotten serious about using map and grep, and suddenly all those awkward foreach loops I've written look like Fred Astaire in Frankenstein boots. Sure, they work, but it's a long way from the most graceful solution!

"All you need is ignorance and confidence; then success is sure."-- Mark Twain