Of course, its already in the tree... see the CVS : http://cvs.winehq.org/cvsweb/wine/dlls/wintab32/
Oh, sorry, I'll clarify:
The CVS currently has stubs (I think contributed by Patrick Stridvall). They were contributed in late 2002/early 2003.
Aric's patch to actually provide functionality (from April 2003) has not yet been applied. He's going to re-work it to have better dll separation. (See his recent post)
Cheers
-Rob.