On its own, the Closure Library isn’t very compelling for the average web developer. The dynamic loading is intended for unit tests and development, and using it in production would cause users to download masses of unused code.
Luckily for us, the Closure Compiler was open sourced at the same time. The compiler knows about a lot of the idioms used in the Closure Library and does a really good job of removing dead code and optimizing what remains. The team also launched a web service with a RESTful API so you don’t even have to run the compiler yourself.
Even with the web service, the development-debug cycle isn’t ideal. So when I found myself wanting to use some of the Closure Library for my new photo site I hacked together a PHP class that provides a convenient interface to the compiler web service, caches the optimized code, and recompiles when the sources have changed. Pretty basic, but quite useful I think.
I know PHP is looked down upon by many programmers, but it is easy, convenient, and widely available. If you have a PHP based site and want to use the Closure Library and/or the Compiler, it might be worth heading over to the project page and seeing if it might be useful.