Well they sure fooled me. I've looked in every French dictionary I can find, I've asked French-speaking friends at work, and I can't find any proof that "jedusor" is, actually, "riddle" in French. Which means that either I am a terrible researcher or Google translation is wrong and the translator of The Chamber of Secrets is too clever.
So Tom Jedusor is a made up name that has no relation to Rowling's original Tom Riddle. That kind of stinks, I think.
And imagine my surprise when I turned the page and found out that the French Voldemort's full name is Tom Elvis Jedusor (which, by the way, turns out to be an anagram of the sentence "Je suis Voldemort", the French version of "I am Voldemort"). I actually snuck a peek at the end of the book to confirm this.
Now, in the original English, his name is Tom Marvolo Riddle, which is an anagram of "I am Lord Voldemort", with Marvolo representing his grandfather's name. Does that mean that the French grandfather is actually Elvis Gaunt (or however they translated Gaunt into French; my dictionary says it's "Decharne"). So maybe Riddle's grandfather will turn out to be "Elvis Decharne".
I know, some of you have already read the rest of the books in French and know what Marvolo Gaunt's name turns out to be but don't tell me. "Elvis" was a bit of a shock but fun nonetheless.