Based on the mounted lens, I would like to have the rear screen display the Depth of Field, and hyperfocal distance information. Since this information is no longer etched as a vernier into the lens, it makes sense to display it in another manner.
I like the "capture -2ev, 0ev, +2ev simultaneously" idea. If this could be extended to focus also - say 3 to 5 focus planes (DOF or focus stacking), that would be very nice.
Some sort of workaround/solution for having to have the black frame subtraction would be great for my night photos (and doubling the time it takes).
Faster and more accurate auto focus. Yes, the K7 appears to be much better than the K20, there is still so much more that can be done here.
Expand the built in time-lapsed / intervalometer functionality.
On the live view provide a better set of grids.
Built-in motion detection - for catching lightening. I know that this might be difficult or impossible with the mirror box as opposed to a straight sensor design. This could be an extension to the liveview functionality.
With the advent of the netbooks, the Remote Assistant could certainly be improved - or better yet, make the USB API be open, so that a new class of remote software utilities can be made available by the open source community. This is one area where Pentax could excel with out spending really any money. This would possibly attract a wide range of folks who current focus is Canon. This could also be tied in with the black frame extraction, especially for multiple shots - let the netbook do it.
Also, with the advent of very large SD cards, place all the external connections (USB, aux power) on the right hand side with the memory card on the left hand side. the external shutter release was moved to the right hand side for the K7, and now makes it very convenient. This would certainly help with L plates and tripod mounts.
I liked that Pentax stopped adding MP (for the K7), and started working on aspects of auto focus and image quality items (ISO). Pentax needs to continue down this path.
Its not my intent to rile everyone up here, but to help attract non Pentax photographers to Pentax, offer a Canon or Nikon setup for JPG. This might also help the reviewers too...