Blogging is like e-mail with access control. Post a blog entry that can be read only by the people you intend to read using access control. Ping them. They use WebID to authenticate and can read it, copying the entry over to their store.
Result: secure e-mail that arrives in a couple of connections at its destination.
Next: write a pop/smtp proxy, so that people can use their current e-mail clients to do their work.
site atop S/MIME.
We call it ODS-Mail :-)
yup, think gmail already has an offering for this, web side imap api irrc