.. in the Movie Mode!:-
http://www.dpreview.com/news/0910/09101403nikond3shandson.asp
The standard ISO range of the D3s is exactly the same as the boosted one of the K-x. But the boosted highest ISO of the D3s is crazy anyway - 102,400! What? :-0
The pixel count is similar too, but there is one important difference, i.e., the D3s has a Full Frame sensor (but of course the K-x has not)! Btw, it is also a Sony one.
Of course for everything else of the D3s, it just blows any of the Pentax DSLRs out of the water so easily. Actually, nothing should and could be compared!
Whilst there is no real "sound" from Pentax for having a Full Frame DSLR sooner or later (but only this last rumour), the K-x is now equipped with the Nikon D90 Sony sensor or its latest variant. It is just a good sign for the K-x case as those Sony CMOS sensors were previously only used exclusively in Nikon DSLRs but now Pentax/Hoya has started to pick it (or them later) up.
Even though Pentax later on uses the FX sensors with low pixel count (just like those used in the D3 and D3s), many Pentaxians' dream for a Full Frame Pentax DSLR can still be realised some days later, hopefully. My wishful thinking.. (I know!)
In the meantime, some Nikonians may now be very "disappointed" with the yet low pixel count and the low video recording spec of the D3s. But then there is also a D3x which uses the same sensor as the Sony A900/A850 and with 24MPs. But then the D3x does have its problems, see:-
http://ricehigh.blogspot.com/2008/12/ultimate-whiner.html
Enjoy and have fun!