Can anyone tell me if any of the packaged applications have a mobile UI?
Is there any way to tell, other than by installing, unlocking and examining the UI properties?
Is there any plan to upgrade the packaged apps to support mobile?
You'll have to install and run the application to access the "mobile" button. And if you looked at the application information, you should see the same icons in the screenshot. Hope I'm answering your question.
Just to clarify, the Sample Database Application in APEX 4.2 is using our APEX 4.2 mobile features and this application can be used as a showcase / example for mobile development. Several of the other packaged applications also include mobile pages, however those mobile pages were built based on the mobile features available with APEX 4.1, which were fairly limited compared to APEX 4.2. So while those mobile pages are working just fine, I would advice looking at the Sample Database Application as a reference. With the APEX 4.2.1 patch set we are planning to update the packaged applications to use an up-to-date mobile implementation.