I use a Wacom graphic tablet for note insertion in Sibelius. Granted it’s nothing more than mouse emulation (read: rudimentary and nothing particularly sophisticated), it actually works much better than using a mouse, because it’s more natural and more like writing with a pencil on paper. Incidentally, I was doing the same years before, when I was using Finale. I haven’t used any recent version of Finale, but I’m absolutely sure that graphic tablet mouse emulation works with that software too.
I hope Steinberg’s new notation program will include native touch and graphic tablet support.