Since the release of "beta3" I'm waiting for a real beta release (sencha will call it 4.0 final or so) or even wait for 4.0 GA (sencha term: 4.1).
Before beta3 it was only a communication problem how to use MVC. In beta3 it was completly rewritten (my opinion), the examples and docs are still buggy as hell and there are over 100(!) API changes 2 weeks before the planned final release. I see some potential to continue this renaming madness, as an example with the tab package (Ext.tab.TabBar maybe rename to Ext.tab.Bar). Call the releases pre-alpha and alpha and no one is worried about the development.

westy asked some real good questions. Okay, some are really specific and I'm not sure if the frontend should manage such things (two repos etc).
The simple examples we got from sencha, which remind me of the current iphone/smartphone app insanity even on desktops, hopefully have not the intent to show the "power" of the product.
The example "Phonegap" is fine for SenchaTouch but on desktops this is maybe 1/30th of a complete "app".

Perhaps I'm missing something because I do not play with beta3. I can and will wait for 4.0 final.