I'm continually impressed with sandstorm. I played around with their thing on oasis and it all worked as advertised. It's not extremely polished yet, but the functionality is there. I've been looking into their serialization protocol, Cap'n Proto, for a side project and again it seems quite well designed.
I sincerely hope the future is one in which lots of families, people, etc, self host their own "cloud apps" rather than delegating it all to facebook, gmail, etc, and sandstorm looks like it could be a winner here. (Or maybe owncloud, or that thing that HN blogged about a week or two ago, or...)
We definitely want to build a "Sandstorm App" on mobile at some point, although it's worth noting that it would mostly be a hub for other apps to hook into your Sandstorm server, which to some extent they can do already, as demonstrated e.g. by the TinyTinyRSS Android app which can sync with your TTRSS instance on Sandstorm.
At present most of our apps are focused on productivity tasks (e.g. real-time collaborative document editing) with I think is the kind of thing people still mostly do on desktops. You can totally open Sandstorm and Etherpad on a phone browser, though, and I commonly do this when demoing it to people.
In any case, we obviously have a lot of work still to do, but I hope that doesn't stop anyone from trying out what we have so far. :)
Sandstorm works decently as a web app on mobile devices. Also, certain apps have mobile app support. For instance, Davros actually can use the ownCloud client. Tiny Tiny RSS has an app embedded in Sandstorm (slightly forked) for Android as well. And then Radicale is an CalDAV/CardDAV sync server, which will work with a lot of contacts and calendar apps.
Given the variety of applications one can host on Sandstorm, it's hard to have an all encompassing 'Sandstorm app'. And for what the core of Sandstorm does, the web interface does it well on mobile.
I sincerely hope the future is one in which lots of families, people, etc, self host their own "cloud apps" rather than delegating it all to facebook, gmail, etc, and sandstorm looks like it could be a winner here. (Or maybe owncloud, or that thing that HN blogged about a week or two ago, or...)