Of course the majority of Greensburg only suffered from EF4 damage or lower but I think a few parts got EF5 damage and that's why I believe it should be classified as one. Most of the time the EF5 damage will be very limited and the May 3, 1999 tornado was no exception.
From what I have seen on Fox news today and some of the other pics on the inet right now, it appears to me that this will be an high EF4
Most areas resiceved EF4 damage alright. That doesn't mean it will be rated a EF4 though since we rate tornadoes by the highest amount of damage caused.
Judging from the footage on The Weather Channel and CNN, it seems as if at least in some areas of Greensburg the walls of the houses and businesses were left intact, and the town is still littered with debris. I was under the impression that a signature of an (E)F5 tornado involved "sweeping the debris clean," i.e. no debris piles remaining, just structural foundations. In scenes from Bridge Creek and Moore, all the structures are completely gone and debris has been blown to the perimeter of the tornado path.
Some areas got it worst then others. Parts of that town almost had no damage but that was about 2-5% of the total number of buildings.