Old Paint the faithful Pismo is still chugging along, but I'm interested in what would be needed to swap its guts out with a Mac Mini. Theoretically, it would be the best of both worlds. A dual core CPU able to be swapped for a 64 bit processor when one becomes available, plus the battery life and swappable bays of the Pismo.

As a practical matter, what would need to be done, at what price?

On the back side of the Pismo, the present VGA jack would need to be cut out for a DVI port, and some sort of 2nd video port would need to be made for the 14 inch display in the Pismo. The Mac Mini's motherboard would need to be secured to the frame of the Pismo, and connections to the batteries and keyboard would also have to be cut in. The Mac Mini would have to be connected to the Pismo's power management features, since the long battery life from two full batteries would be one of the major reasons for keeping the Pismo.

Anyone interested in taking on such a project? For how much?

My guess is that the Mac mini's board will be too tall to fit into the Pismo, so don't keep your hopes up.

Wow. Nice idea, bit ambitous I suspect. I can attempt to tackle a couple of issues.
The screen is a big problem, unless you can find the exact pinouts of the Pismo LCD (and there are two, though I suspect they are similar). You would need to build a converter to run the LCD from DVI since the Mini has no other video output. Maybe you can find an old external 14" LCD to use instead. (Swap the panel over with the Pismos I mean, not run it as an external).
The drive cables are a straightforward rewiring job, but the power management is likely to be a fairly monsterous task I suspect.
Aside from that you might need to alter the angle of the RAM slot on the mini board. Thats not such a big deal though.

Good luck. I wouldn't fancy tackling the power management myself.

Echoing what war has to say, video would be one of the primary problems. You'd adapting the display to the port on the back, or soldering to board inside. Likewise, you have to think about powering the display, which might be a challenge.

Similarly, you'd be needing to try and adapt the Power Interconnect board in the front of the pismo, to transfer trackpad information, as well as battery and optical drive information. Honestly, I dont know if thats doable. But, I wont be any more of a killjoy than that. If you think you can make it work, go for it and impress us all

Maybe you could totally gut the Pismo, and use a USB trackpad. Video would be tough, but definitely doable, I'd say the easiest would be to get a 14" external display and take it out of the casing, adapt the cords etc. So power management is what's left. You can get DC transformers if you need to step up or down the power to the display, and i've seen a couple of mini's modded to run on batteries. Sounds like a fun project, good luck if you go for it.

Trackpads from the later PowerBooks are USB based, the Pismos is based on ADB. That should make life easier.

A better way to do this might be to use the Wallstreet Case. I have an extra case just for doing this but have yet to decided to do it (nor devote the money to it yet lol)

You will have more space and screen options with the wallstreet, and I am sure with small mods a 14" ibook g4 screen would fit among other changes. *shrug*