What are good tools/frameworks for i18n of a php codebase?

Question

I have been looking at a few options for enabling localization and internationalization of a dynamic php application. There appears to be a variety of tools available such a

Answer 1

There are a number of useful extensions in pecl: http://pecl.php.net/packages.php?catpid=28&catname=Internationalization

In particular, you may want to check out php-intl, which provides most of the key i18n functions from International Components for Unicode (ICU)