In an interview with Ruben Donis (chief, molecular virology and vaccines branch, CDC) ScienceInsider got a couple of answers that touch on points that I (and lots of others) have noted:

Q: Have you been able to compare isolates from Mexico and the United States?
R.D.: Yes, they are very, very similar. Many genes are identical. In the eight or nine viruses we’ve sequenced, there is nothing different.

Q: Have you compared someone who died with someone who had a mild case?
R.D.: Those data are still slippery. We don’t have good case data. You get age and sex—very limited information. That’s a problem. In the set of samples we know one case was fatal, but we don’t know which one it is.

So, nothing concrete; the circulating Mexican flu probably isn’t different than the sequences we’ve already seen; and reading between the lines at least one fatality wasn’t associated with an unusual viral sequence — though we don’t know how early this case was.