Please consider to vote for Sisulizer at delphitools.info/2012/02/15/what-do-you-use-for-string-localization-in-delphi/ as your favorite localization tool.
Currently Sisulizer is doing well. GNU gettext/dxgettext is still leading.
If you do not already know: Sisulizer does support localization of PO/POT files, too. And I know that quite a few translators are using Sisulizer to translate, even when the developer just use GNU gettext. Why? Translators love the comfortable and intuitive user interface, and all the great filters, search/replace features, integrated translation memory, and the validation functionality. Especially the validation features help translators and developers to create great, and save localized versions of your software. Please read more in the following articles about localizing PO/POT files created by GNU gettext routines with Sisulizer: