This question came up on forum recently (I can’t recall which forum, sorry) and it interests me because multilingual SEO is something I quite enjoy.
The question as I recall it is whether on-topic links in various languages or from various language websites is helpful for SEO purposes. The answer is not clear-cut.
First, any link is a good link…almost. That is, unless the linking website is truly despicable (Did I spell that right, Sylvester?), the link carries some value.
Second, in many niches Anglicisms creap intot he lingo. For example, SEO is a word used in Spanish and therefore a link on a Spanish page about SEO would be keyword relevant for this blog.
Third, you can always include a bilingual link, so a link on a French page to an English page about restaurant jobs could read “Emplois Restaurant Jobs”.
Fourth, it is possible that the search engines can relate some cross language themes. There are plenty of carpet websites with sections in several languages. There are plenty of car accessory websites with sections in several languages. There are plenty of hotel websites with sections in several languages. The major search engines are smart enough to recognize patterns, such as that very often English sections of a website themed around “carpets” and “rugs” also have French sections themed around “tapis” and Spanish sections themed around “alfombras” and “tapetes”. I am not saying that Google and Yahoo actually do this, just that they can. They can probably also tell which sites of various languages might be similarly themed by their link profiles, for instance if the websites were both linked from a lot of directories or blogs in the same niche.
Fifth, keep in mind that there are a lot of multilingual people out there. There are many people in my neck of the woods who would click on a link whether it is in French or in English.
Your best bet – the most sure thing – is to seek links from websites in the same language. But if you see a good opportunity to get a relevant link from another website in another language, don’t feel you have to pass it by.