I'm currently burning the midnight oil and working hard on a project that I'm building for myself ( my very own bootstrapped startup ) and going through the motions of whether to internationalize the whole application. I'm keen to abstract the site's copy and text away from my views but whilst doing that I'm aware that I've done a large chunk of work towards fully abstracting the language of the site away from the internals.

Has anyone had any success stories of offering their product in say French or Italien to find that there was a large audience of non English speakers just waiting to find get hold your application?

The product I'm building is a Programmer Portfolio Network so there is no limit to it being focused on a particular locale but ( and this is going to sound bad ) is it really necessary to provide for languages other than English if your target audience is Web professionals?