I tried to have a bash at using the ipad in the workflow for the webcomic... sadly it's not quite there.
I inked up the pencilled sketches as normal with real ink and scan in using photoshop...
to get it into the ipad in a form that sketchbook pro can recognise I need to import the artwork as a .png into iphoto, connect the ipad, sync the last iphoto import, and then add it as a layer.
The size of the image is limited to 2048x1536, which isn't too bad as it's close to A4 at 185dpi... I usually work on the original A4 scan in B/W at 600dpi, and reduce to 300dpi to colour, eventually dropping it right to 150dpi, or 72dpi for final output.
Multitouch to drag the image image and resize is quite easy to get used to, and the undo button is close to hand when the screen doesn't register two fingers, and runs a brush line through the work.
Brush control, via the puck, covers size and opacity, with a stab of the brush button needed to change colour, or the side palette. It's all eminently do-able, right up to the point I started trying to do some fills with the bucket tool.
It just wouldn't play ball.. at first I though it was the slightly hit and miss pogo stylus, which makes the whole process a bit like painting with a dried out board marker.
Whatever the issue, I just couldn't get the fill to work where I wanted, when I wanted. I will persevere, but think the benefits are probably in sketching, rather than the proper production cycle.