Scientists from the Mayo Clinic and University of Illinois have generated red blood cells from stem cell precursors. The really interesting thing about it is that this technology promises to eventually produce type O negative blood, which is the least likely to result in a transfusion reaction.
In the otherwise excellent article, the author makes one common mistake:
People usually require blood transfusions that match their own blood type: A mismatch can be fatal. Type O-negative can be safely transferred into anyone, but is only possessed by about 7 percent of the population, leaving supplies perpetually short.
If you can't spot the error, read this short post ;)