The Chirpy! project originated mainly out of frustration caused by the Rash Quote Management System, due to its numerous bugs and its lack of efficiency and extensibility. While its developers openly admit that it was a quick job, eventually, this became unacceptable.
Chirpy! is written in OO Perl, allowing for extensibility and even instant portability to non-Web platforms, uses a pluggable backend (the default being MySQL) and outputs valid XHTML 1.1 and CSS level 2.
If all that gibberish doesn’t convince you, you may want to check out one of the demo sites and see what makes Chirpy! so darn cool.