Ext.ComponentQuery.query() is an amazingly powerful and useful function. I've been using it all over the place. The only problem with it is that it's a pretty long name for something that's used so often - in jQuery, for example, a roughly analogous function is aliased to $() for convenience.
So, since I couldn't find anything in PR3 regarding an alias for this function, I created my own:
Perhaps the Sencha team would consider including a similar alias in the final version of Sencha Touch 2?
/* Create alias "Ext.cq()" for "Ext.ComponentQuery.query()".
var applyButton = Ext.cq('[action="apply"]', this);
Ext.cq = Ext.Function.alias(Ext.ComponentQuery, 'query');