Another wishlist item would be to be able to use the pattern mechanism for picking between long and short s forms (won't help in the case of "Wachstube" which can have either depending on meaning, but should work for most other cases).
There's an interesting related issue: I've always wondered if it was possible to adapt the pattern mechanism to handle the cases where you don't wish to use a ligature in German (like in “auffallen”). I suppose it would need a different dictionary (you probably can't use the normal hyphenation patterns – that's my guess only), but it surely would be legitimate to instruct TeX where not to set ligatures in some languages. Then we can devise a similar dictionary to automatically correct the “oe” into “œ” in French :-) Arthur