Journal: Multi-language web applications in PHP?

I am going to build a web application in PHP. The application needs to provide the user interface in several languages, and will have rather complicated application logic including database access. Of course I will separate the logic from the presentation, but what is the best way to implement multi-language support?

I've briefly tried using gettext together with plain PHP files in the presentation layer, which works but makes it hard to use HTML editors for editing the user interface. Another option would be to simply make a copy of all presentation layer files for each language. I'm sure there are better alternatives.

If you have any experience with multi-language PHP applications, I would really like to hear about it. Which techniques did you use, and how did they perform in practise? Thanks in advance.