They're found under various different names, most commonly "bird's eye chili pepper", "thai peppers" or (in certain circles) "LED peppers". Even the mildest thai pepper is typically a good deal hotter than the hottest jalapeno, but of course peppers vary by climate, cultivar, etc.

I'd say these guys are like a really mild habanero, heat-wise, but their flavor is entirely different. It's got less fruit, more tang than a habanero.