I actually kind of asked this in the other thread... so I'll follow it up here. I've found a very good library (I'll find the link later if I think about it) for Excel docs, but nothing for word, and it generates Excel docs on a Linux server, so I don't see why it couldn't be extended to other types of MS documents on any server.
After all, what I'm gathering from the approach of MS on this project is more about connectivity with MS products outside of the actual server. It seems to me that they are expanding into this market to further the dominance of their file formats and other products, rather than just attempting to overtake the hosting/server market.