Probably - the words Cat 5 have a tendency to cause mass hysteria. With a pressure now down to 910, though... there is no doubt. The only question is where specifically she'll end up and how much strong she will get. A few miles east or west will mean a lot in terms of where the destruction occurs - not if it occurs but just where.

It appears to be gradually turning - weather channel has a plot where they show the line, and it's definately right of the previous track - headed for the big easy or slightly east.

EDIT: With a pressure of 910, if my memory is correct, Katrina is now the 3rd strongest hurricane on record - only Camille (908?) and Gilbert (897?) had lower pressures. I'm using my memory so this may not be the case.