we've done elasticsearch for RT analytics for about a year back in the 0.16 days, it was not stable to say the least for us and we've been using 7x m1.l AMIs at the time..
Today were aggregating the data in hadoop and bringing down only that to elasticsearch basically for a heavy use of the statistical facets.
The company I work for ( http://mobile.conduit.com ) also utilize phonegap for tens of thousands of apps, and it has been mainly good for us, allows us to really go cross platform and build a thin native client around it to perform some brilliant looking apps!
Today were aggregating the data in hadoop and bringing down only that to elasticsearch basically for a heavy use of the statistical facets.