for proof of concept, I created a Sencha Touch 1.1 client for Moodle 2.1+.
You can find it on Github.
You will need to cherry-pick a JSONP server that is not integrated in Moodle. You can vote for the MDL-29913 issue if you are interested by a JSONP server in Moodle.
Some pictures of the client:
Note: I tried to embed this app into an iOS app with PhoneGap, and it does work well.