currently the iphone app doesn't attempt to send data at all when there is no data connection or the iphone is in airplane mode. (There is a setting to do this)
This setting seems to be a hack to prevent attempts to send data when there is no connections. This shouldn't be a setting, it just shouldn't send data when there is no connection. It should queue it.

A setting to set preferences of channels over which to send data would be great. This would allow students/teachers to avoid abusing their expensive connections and send everything when on the school wifi or preferred wifi. It could get more preferences , but for now choosing between 3G and wifi would be very practical imho.

for example:
Data connections:

• [on/off] send data over 3G or via mobile broadband service.
• [on/off] send data over wifi connection.

with this we can explicitly control what the app senses as a valid data connection to send data through.