Thanks Rapaire the links at the bottom of the CDC page are great, e.g.
"We know so far that the viruses contain genetic pieces from four different virus sources. This is unusual. The first is our North American swine influenza viruses. North American avian influenza viruses, human influenza viruses and swine influenza viruses found in Asia and Europe.

"That particular genetic combination of swine influenza virus segments has not been recognized before in the U.S. or elsewhere. Of course, we are doing more testing now and looking more aggressively for unusual influenza strains. So we haven't seen this strain before but we haven't been looking as intensively as we are these days.

"The viruses are resistant to amantadine and rimantadine anti-viral drugs but they are sensitive or susceptible to oseltamivir and zanamivir, the newer anti-viral drugs for flu. And at this time we don't know exactly how people got the virus."

Death rate for all lab-confirmed cases is zero so far.