I was fortunate enough to be at the event last night for the introduction of the K-x, and briefly got to handle the K-x. The form factor is largely similar to the K2000, it's very small,yet not compromised in handling. The grip is quite nice, nicer than the competitors at this price point. Build quality seemed quite nice, despite the addition of plastic inside, and the paint quality of the red, white, and navy offerings looked and felt top notch. Interface looks in line with the K-7 and the performance seemed inspired to, I'll say 4.7 fps feels pretty good especially at $650. I took some shots at ISO 6400, and zoomed in, they looked potentially usable, certainly ISO 1600 will get some use out of this camera. Pentax didn't make any claims to improvements in noise management when asked, but suggested there may be improvements over the K2000. The only oddity was the widely discussed AF points missing in the viewfinder, which led me to check the settings and scratching my head momentarily.
Other than that, the K-x looked very solid, If you just go down the spec sheet and comparison shop at this price point, it'd be very hard to overlook the K-x, a point that Pentax was keen to mention (same with the K-7)
For more on the camera, and the presentation, including the Pentax gameplan, and relationship with Hoya, I posted my hands on
here.