See what our knowledgeable Russian Engineer and Pentaxian Oleg V analysed and explained:-
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=36859818
Oh well, whilst I don't find any flaw with Oleg's arguments, I think a real-world DR test is still required to find out the truth. So, let's wait for DPR's result, as I believe their DR test is closer to real-life and should be more meaningful.
Or, if you are just a K-5 user, you can follow the methodology and test adopted by that D5000 user as quoted by Oleg V, and the *usable* DR of the sensor/DSLR can still be found out briefly. Btw, I still prefer DPR's methodology of shooting a lightness "stair" simultaneously (and of course) as this is just what we want for the widest possible DR practically in daily shooting.
But if the DR of the new Sony sensor (of the K-5/D7000) is just measured to be lower later on, then it is just sad that now even sensor maker also does trick(s) to optimise their hardware for *benchmark*, which is just nothing about real performance, subsequent to what display card chipset/GPU makers have been doing this for years already, say, for the 3DMark.