Seattle, Washington based Alivecor will be showing off its new iPhonECG system at the upcoming Consumer Electronics Show in Las Vegas.
The company has partnered with Oregon Scientific to manufacture the units, which are expected to sell for under $100 a piece.

Link: http://www.alivecor.com/index.htm
Reference: http://www.medgadget.com/archives/2010/12/ecg_attachment_for_your_iphone.html