I think that before we get this, we need the universal auto-correct mentioned previously. Punctuation, but also auto-correct when typing. Somewhat like predictive text for a QWERTY keyboard. For instance, if I'm typing the word "typing" and I enter "typinf" I would hope that the Tablet could recognize that "typinf" isn't a word, but that the "f" is near the "g", and "typing" IS a word, and automatically change it for me. THAT would be MILES more useful to me than a transparent keyboard.

Yes, but don't worry, I was too for quite a while.
Two things actually, both described, rather confusingly, as handwriting gestures in the documentation. And they both work in the stylus-board, and in the thumb-board.

• To "shift" a character, press that character, and drag vertically upwards for about 1 key-height. The character will be inserted uppercase (or lowercase, if caps is on). This also works for symbols, like :; \/ "' on the thumb-board, and the numerics on the stylus-board.
• To backspace, press any key, and drag to the left at least 1.5 key-widths. Doesn't matter what key, it backspaces one character.

The latter seems a bit wierd. You have a big fat backspace key in both keyboards. In the thumb-board at least, why not remove the backspace key? You would have a full-width slice of the screen at the top. Use it either for a larger typing buffer, or better, show a slice of the screen, kind of like the stylus-board does. This would allow seeing IM responses, which is one of the main reasons people seem to want transparency.
Once you get used to tap-drag typing, you'll find it's excellent.

As for your design, icerabbit, I think the built-in board wastes too much space, and you waste even more. You have 2 shift keys, and a caps-lock. I see no need for more than one shift key. One tap for shift next key, Two taps for caps-lock. (One tap exits caps-lock.)
The selectors for the 3 keyboard panes should be smaller than stock -- I don't need to hit them with my eyes shut.
Your spacebar is huge, I can understand the built-in one being 2 normal keys, but I'm not sure why you have it as wide as 4 keys. And even your normal keys are wider than the stock ones.

If you change all that, then you'ld have room for even more keys, which I would like.

I don't really see the point of shifting rows to get a qwerty layout, unless you plan to perform nearest-match analysis of some sort where if you're vertically on the border between 2 rows, and horizontally on the border of two keys in the top row, it knows you must have meant the key you're centered over in the bottom row. I guess that might help.
But I don't try typing without looking at the keyboard , so I have no trouble with the rows being non-staggered. The only argument I see for qwerty is so you know which area of keyboard to look for a given key in; final acquisition is by eye anyway.

Just my 2 bits, and meant in the best way.
But I think the lesson to be drawn is this: Nokia should let us define custom keyboards, then we would all look like: