Cellular Data usage iPhone 3G

Is there any way to see what data is being sent over the cellular network?
After upgrading to 3.1 OS my battery life has dramatically decreased (like reported on many other posts) but a few other clues cropped up at to why this is.
If I place my iPhone next to a speaker it buzzes away nearly non-stop now (it didnt do this before). I mean every 5-10 seconds its sending data to the cellular network... no surprise battery life only lasts for 4-6 hours now. Also when on Roaming my £30 credit disappears in 1 day without me running anything.
Does anyone know if there is a way to view the data thats being transmitted? Id like to know which application/service is responsible and perhaps seeing the data will answer this. My guess was email as using exchange but transmitting 10Mb of data abroad a day for email (when not receiving anything) seems excessive)
(Just to highlight this was all fine before the recent OS upgrade)
iPhone 3G iPhone OS 3.1.2 Win XP & Mac