Modal "Loading..." dialogs not good UI decision?

Question

I've read on Reto Meier's blog that he doesn't recommend the use of modal "Loading..." dialogs in Android applications. Is this a general consensus among developers?

If I have a login screen what should I display when the user tries to sign in? Until now, I have used a "Signing in..." indeterminate progress dialog. Should I use the application's progress bar? Should I use a Toast?

And, in the general case, when should I use dialogs and when not to?

Answer 1

It seems that Reto Meier has recently addressed this issue. http://blog.radioactiveyak.com/2010/08/what-you-can-do-with-your-modal-dialogs.html

Basically, the idea in the article is that, generally, modal dialogs are the lazy developer's way of avoiding synchronizations/updates.