Sometimes the settings page will show I'm connected to a particular Wifi network SSID, but the 3G logo in the top left hand corner still appears and I still appear to be downloading via 3G.
What's going on here - is this a caching issue? A wifi connectivity issue? Is this a feature?
-- edit
This is on an iPhone4 with 4.01 - although I've seen it in the past on an iPhone 3G on 3.01.