From a very proprietary point of view, this thesis mentions: «If source code is available, tools and techniques, with varying quality of internationalization, can be used to internationalize an existing monolingual product that minimize costs and improve
efficiency. This includes the use of lexical analysis as shown by Peng et al., automated
identification of “need to translate” strings as shown by Wang et al., and the use of tools like GNU Gettext. See 4.4.5 and 4.5 for details.» http://publications.lib.chalmers.se/records/fulltext/161183.pdf