Sencha touch 1.1.1
Running an iPhone app on iPad in 2x emulation Ext.is.iOS return false, even of course we are on iOS, working fine with universal app or iPad app.

Mac OSX Lion 10.7.4
xCode 4.3.3
Sencha Touch 1.1.1
Phonegap 1.8.1

I dont look at the code in Sencha Touch 2, but if you test navigator property the same way, Ext.is.iOS will return false on Sencha Touch 2 too.

Using Ext.is.iOS in an iPhone app will cause unexpected result on iPad and this will cause the rejection of the app on appstore, because they test that the app is working fine also on iPad.
Off course was my fault to not testing the app on iPad in 2x emulation, but this a bug in Sencha Touch...