Microsoft Research and arXiv.org have been working closely on the adoption/utilization of the SWORD protocol and arXiv.org already has a preliminary service up and running. I would encourage you to follow-up directly with Simeon and Paul for additional detail, but I think the bulk of the work is largely done.
In an important related point, I would like to add that we (Microsoft Research) is actively working on the ability to push from Word 2007 directly to repositories that can consume the SWORD protocol.
The service is open to all file formats, article submissions can be of any format, as configured as part of the site settings. On the archival side, the service supports depositing into any Information Repository that uses the SWORD protocol (for example, the ArXiv repository and EPrints based IRs).
These are both encouraging developments for repository interoperability.