I’m in the middle of translating the WP Super Cache plugin (one of my goals before a 1.0 release). The docs make it easy to understand how to do it, but it is such a chore when there is so much text. According to Vim, I’m about 25% of the way through wp-cache.php
Checking to make sure that all the strings are translated is tiresome but the Pig Latin plugin makes it easier to spot untranslatable strings:
There will be a new release of supercache soon, but check out the download page and grab the development version if you want an exclusive look at the new debugger, “newest cached files” listing and bug fixes.