aptosid seems to work! (It is the successor to Sidux). It uses 2.6.36 kernel, whereas my Deb install is .32. So maybe this is a kernel issue? Thanks for the refs, didn't find them under my searches.
The interesting difference is that under Natty, when you invoke the gnome mouse configuration tool, it brings up the touch screen as a mouse. On Squeeze it does not.
Peter