I am brand new to Android - just purchased a Motorolla Atrix - and have a very small data plan with AT&T. If I plan a trip from my home (using my wi-fi connection), are the needed maps cached to my phone at that time? (how about short trip versus a lenghty trip?) Is there a way for me to tell during use if the application is "pinging" my data plan? I want to use this functionality, but am concerned I may find it expensive to actually use.