Serial Cables Illegal Due to DMCA?

Colin McMillen writes "I've recently had an interesting run-in with the DMCA... apparently, US Customs has rejected entry of a PC<->Sega Dreamcast serial cable into the US, supposedly due to copyright violations. This cable was to be used for Dreamcast programming for the Real-Time Systems class offered at my university. This seems to be a clear case of the DMCA abridging a perfectly valid educational use of a perfectly legal piece of hardware."