Actually, I believe electronic dictionaries have been available in the US for a while. My mom bought me a Spanish->English one when I was in 4th grade, and a bunch of middle schoolers owned electronic ones with German, French, Italian, and Chinese. They were popular in my elementary school, but after entering middle school, I ended up being the only kid with an electronic dictionary. :\

They're definitely on the market, but in comparison to iPods and PDAs, they're pretty difficult to find. Pity, since an electronic dictionary is oodles more helpful than an iPod (and I happen to heart iPods).