[reidrac]

Liferea supports Tiny Tiny RSS sync, so that could be it. You can host http://tt-rss.org/ and use Liferea as desktop app (and may be the web interface for mobile).

In fact that's the only part that I really liked of Google Reader: it was the perfect backend (I got used to the web interface, but the real experience was with the native apps).

It would be nice to have a "standard" API for RSS sync that could be implemented by servers and clients. In that way we could host our own RSS backend in the same way we run a SMTP and IMAP servers to have our own independent email infrastructure.

Tiny Tiny RSS API could be a good start, or we can agree on a Google Reader compatible API.