Engadget provides a hands-on with the forthcoming iPhone firmware 2.0. Among other improvements, one is now able to select several items for deletion in the Mail application.
Weirdly enough, a symbol which resembles a radio button has been chosen where the actual functionality of the widget is that of a check box. The likely reason is that throughout the iPhone, the symbols used in the lists are round-shaped but still I’d consider being consistent with conventions more important than being visually consistent with the rest of the UI.
Once a message is selected, a tick symbol appears, hinting towards check box kind of logic.
For comparison, here are the widgets that iPhone uses when rendering web pages.