no the 3g and wifi icon wont ever appear at the same time. only 1

if u on 3g n off wifi, and u get a 3g signal, then the phone will use 3g connection. the 3g icon will appear at the status bar

if u on both 3g and wifi, ur phone will look for wifi 1st bcuz this is the priority. if it can connect to a router (even though the router is not connected to the internet), then it will connect to that router and 'ignore' the 3g signal. so at the status bar only got wifi icon, no 3g icon even tough 3g is on

i only on wifi at home n coffee shops like that. most of the time i turn wifi off because sometimes my phone tend to connect to routers like my campus wifi (can connect, but need password before surfing). if this happens, my phone will be on wifi, but no internet n ill miss my whatsapp messages ;p

so basically u need to turn off wifi to use 3g signal

priority goes to wifi 1st that is why even your wifi is connected but you on 3G it will still be on wifi connection. And no when you are on wifi it will not show the 3G on status bar till you off your wifi or you are out of range from your wifi. I donno this applies to iPhone 4 only or it might be a iOS version. I am on iPhone 4 ios4.2.1 btw.

iOS 4.3.2 feels the same to me. those apparently suffering bad battery life, any good news?
yeap from kuching, BDC area. but now in miri. u?

my one also sumtimes like that..means if u on personal hotspot at General -> Network then baru ada balik dkt 1st page..haha

wont be lost..
J.B 4.3.2 out ..

Others answered by alvinool except bluetooth transfer. You can try ibluenova or iBluetooth via cydia.

Its working fine on my friend's i3g thou. Not sure for others. You can opt to try it out and give feedback on it. We are eager to know too.

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Added on April 23, 2011, 9:02 am

Cydia apps are outdated without realizing it. Suggest you to download from iTunes store.
Let me recommend you Bluetooth app to transfer photo & contacts iDevice to iDevice. Bluetooth Photo Share