Why my PDA is an iBook, and what the next one will be

I had a Palm III for a while, but I didn't really use it. Today, I have an iBook, and I use it as a PDA more than I ever did the Palm, because it's a real computer and I don't have to worry about synching it (which never really worked right for me). The thing is, in most situations where I can afford to devote both hands to computing (one for the PDA, one for the stylus), I can afford to sit (or squat) and take out my iBook (I'm typing this on the bus right now). The Palm wasn't more portable in the sense of being more convenient to use, just in the sense of being smaller and lighter, and I have a nice, padded computer backpack and routinely pack my iBook when I'm going anywhere except shopping.

So, what would qualify as more portable than this iBook? ( A real wearable computer would. )