while the pismo is/was a great machine, i don't see the need for such a design anymore.
i have a zip drive. havn't used in in several years. i don't see the point in being able to get one internal if there is such a small need for it. when i had a 3400/c, i used my internal zip all the time, but now with high speed wireless networks, i see little need to physically move a few hundred Mbs when i can do it over the air. If i need to move many gigs, I burn a dvd.
as was said, i can upgrade my hd, so i see no point in needing multiple in my machine. but- if i do need that extra space for video or something, i have a 2.5" external drive which gets its power from my powerbook. it is tiny, so it isn't too hard to bring with me.
the ability to use two batteries at once is nice, but i can just put my laptop to sleep and swap batteries in 10 seconds. that is pretty close to the same. and, once again, as was said, the next gen of batteries will hold more charge and this need will disseapear mostly.
the upgradeable processor is nice, but i have never been one for upgrading a proc. i would rather just put my money towards a new laptop than upgrade just one part of a whole. when you do a large jump at the proc, the bus bottleneck gets even worse...
so- basically, the only gain i see by the pismo's design is the ability to have third party internal drives. i would never use the feature, so i see no point.
ymmv