See this latest report by this user:-
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=32886371
Is this just a coincidence or Pentax/Hoya has already succeeded to use the firmware to *hide* the lighter vertical line (not always in "green" colour actually, read here for some of the previous bug reports by different users and the details)? I think time will tell.
But since this is very possibly a hardware issue, I don't think software (i.e., the firmware) can completely "cure" the problem. Even if the line does not appear now with the same camera (i.e., the hardware), the software could only do tricks to hide it when it is detected! Who knows if there is any loss of image data as a result? E.g., by simple interpolation using the data of neighbourhood pixels around the line.
However, as long as Pentax do not officially announce that there is a new firmware to "cure" this well-known problem now, such an individual user report on how possibly a "new" (still in version 1.01) firmware is the solution to the issue may be just not so conclusive and it is indeed too early to draw a conclusion like that. In fact, have Pentax/Hoya ever admitted that there is such a problem so far? .. even though it has been widely reported and proven - there have been so many samples posted to illustrate the issue already.
Update (10-3): The Green Line is Persistent!
http://www.dchome.net/viewthread.php?tid=760521
(Post in Traditional Chinese)
The user writes that the latest firmware 1.01.00.09 actually does NOT solve the problem. A green line will appear whenever he uses the Live View function, regardless of the temperature of the camera (which is recorded in the EXIF).
Update (10-9): The Green Line is Persistent! (But it has been reduced.)
http://forums.dpreview.com/forums/readflat.asp?forum=1036&thread=33263922