what firmware are your running now? (press menu button then turn on the camera while pressing menu button, should show firmware version)
i've updated as they came out, the most significant one was 1.10 and 1.11 as it added a lot more functionality and fixed some bugs. the ones after were minor ones such as support for SDM lenses......
If your still on the release firmware then yes, update. i think it's safe to say 98% of us k10 owners in here have updated the k10's
here's the version matrix as seen in the pentax website
Pentax Imaging - Software & Firmaware Updates Quote: Version 1.30
* Added compatibility with the supersonic motor drive of Pentax SDM lenses.
Version 1.20
* Added the required programming for compatability with the Pentax Remote Assistant 3 software.
Version 1.11
* Improved multiple exposure function when shooting in RAW.
* Corrected an issue with luminescence control and trailing shutter curtain sync when using the built-in flash.
Version 1.10 (CLICK HERE for a PDF containing more details on v1.10 changes):
* Using the camera's built-in flash, you can now wirelessly control external Pentax flashes. Previously, you needed an accessory flash mounted in your camera's hot shoe, but now the built-in flash can act as a control flash.
* In autofocus select mode, you can program the AF button to instantly return to the center autofocus point.
* In Tv or Av mode, you can now program the second e-dial to adjust your ISO setting.
* In any exposure mode except Sv and TAv, you can change your ISO setting with the front e-dial while pressing the OK button. The camera will display your ISO in the viewfinder and on the top LCD panel as you adjust your setting.
* In TAv mode, you can program the green button to return to the camera's program line. Previously this functionality was only available in M mode.
* You now have additional options for programming your e-dials in P mode.
* Pressing the green button while adjusting flash exposure compensation will now return you to the default value.
* Corrected an issue in some rare cases where a long exposure might produce a vertical stripe.
* Corrected an issue where the battery charge indicator would sometimes show empty in bulb exposure mode.