My understanding of the low carb diets, depending on which one you're following, is that low sugar fruits like berries are allowed. I'm sure there's tons of information on low sugar fruits on the internet. HTH
As Michele said, some fruits are probably allowed. It's all up to you, though, right? You may want to look up the glycemic index. You can find the index number for lots of foods, including fruits.
I just did a quick Yahoo search. Lots of links, here is one: