Yeah, I thought it was steel...or more acurately, I never heard any fuss about it being aluminum...so just assumed it was steel, but sure enough...it is. Okay...How much of a geek am I? I just corrected the WikiPedia entry to read:
"The Insight is assembled at the Honda factory in Suzuka, Japan, where the Acura NSX and the Honda S2000 are also assembled. The Insight and the NSX are aluminum bodies, while the S2000 employs a steel body."