K20D firmware version 1.01 is designed to cure the hot-pixel problem we and others had observed when shooting with the camera's 2-second self-timer function. This was a problem that strongly affected reviewers but relatively few normal users, as we're the ones who are most inclined to use a short self-timer to avoid camera shake (even on a heavy tripod) when shooting test images.
The new firmware patch takes the K20D's firmware to version 1.01. It's available from the Pentax Japan site as a 7 megabyte download. The download and full instructions for applying it can be found here. Note that Pentax recommends using a fully charged battery if you attempt this firmware update: It's easy to imagine dire things happening if your battery died with the firmware in a partially-patched state.
In our own tests this patch does appear to eliminate the hot-pixel problem we saw in our shots taken with the 2-second self-timer.
Our in-house testing suggests that the K20D still has a minor problem with "phantom" pixels of the sort we initially saw on the K10D, albeit at a dramatically lower level than appeared on the earlier camera. The image below shows what the phantom-pixel problem looks like, in a test target image magnified 200% in Photoshop. These remaining artifacts appear to be the result of the substitution algorithm for dead sensor pixels guessing wrong when confronted by abrupt vertical contrast edges. We've thus far only found them in artificial test images of the sort shown above: We've seen no sign of them (yet, at least) in any of our normal test subjects.