To the OP - your post seems to indicate a revelation but I'm not sure what you think it might be.

I only have the option of choosing 2G, 3G or dual from my status area and although there is a mild increase in battery life with 2G it is still nowhere near what you are reporting.

The only widgets/running things that use internet with any regularity is default mail client checking gmail every 30min + the weather widget.

I can easily get through a day of uni/work without recharging with moderate use but no way could I make it more than 24 hours. Would love to know your secret.