Piko,
Thanks for the feedback and your suggestion.
I think you are being mischievous with your Mac-Windows comment. Giving user feedback is not a 'Mac' vs. 'Windows' thing. Providing feedback is good design, period. If an app appears to be hung but is, in fact, doing something - then the lack of feedback to the user is poor design.
I have worked on many websites, new media projects and games, etc. If you watch a user use something, they will get easily confused and frustrated if they don't know what to do next - i.e. a confusing interface and lack of feedback. 9 times out of 10, they will not take the time to figure out what's going on and they will quit.
This is my point in regards to WeatherBug. It looks to me like it isn't working, so I stopped using it.
On the Mac desktop, you see a spinning colour wheel to demonstrate that the computer is 'busy'. On the iPad and iPhone, there are spinning network indicators to tell you it is 'fetching data'. Some apps put a spinning motif in the middle of their app, when it is busy working. This is good design practice.
'Plastering the screen' is clutter on any platform. The iPhone had such small screen real-estate that 'plastering it' would be very difficult. The iPad does not... so it remains to be seen if this discipline will be adhered to. Not all app developers adhere to the same model of UI design, so this will be interesting to watch. European developers often do things differently than their American colleagues. Look at the BBC, Guardian and FT apps to see what I mean. All three are in the news business but they have very different ideas about how to present the news and do not follow a common display model.