Not that I call it apples to apples ...but ...I have used smartphones for quite a while. My last, before the DINC was a BB Storm. I could go two days without charging.
I had the same phone. But compairing:
Storm:
Qualcomm dual core ARM11 400MHz/ARM 9 279Mhz
196MB ROM
128MB RAM (Out of which we had very little of that to actually use for anything!)
No internal Storage
Low Res Screen (480x360 TFT)
3.2MP Camera single flash
to
Incredible:
Qualcomm SnapDragon 1000MHz
512MB ROM (We get to use it all)
8GB Internal Storage (We have 6.6GB usable)
Hi-Res Screen (800 x 480 AMOLED)
8MP Camera dual LED flash
Is far from not comparing apple to apples. That like comparing an Apple to the whole tree. The BB Storm if you take out all the data crap and just play a similar game has almost 2/3's less processor. So actually if your storm got 2 days and you Inc. gets only one technically it's an improvement. Not to mention all the other stuff.
Bottom line is battery tech isn't keeping up to consumer demands. We want faster longer lasting devices. They can give them, but we also want them smaller.....well they can't pack a huge battery into a smaller case....yet.
So will we see a battery life increase out of Froyo? Yes. Why? JIT makes the processor fit in twice the calculations per clock making the phone more efficient. Will it be drastic? Don't count on it. I think most guys who have tested and really looked into the battery issue have determined that the phone quits running off of wall power once it reaches a 100% charge. And if your phone is still on depending on what you have running, you will see it update and show 93-95% power after a few minutes. If this is so it is a hardware issue, that is timed by software. Will they fix it? I hope so.