And by the way, batteries are a finicky thing. IMHO no two battery experiences by users are the same.
Some people don't properly charge the battery when they first get it.
Some people may have a bad battery, with defective cells.
Everyone's phone use is different, but everyone says the same thing, "I hardly use it, don't use it that much" etc., etc.
Batteries, regardless of brand or quality will wear out, lasting three to five years. Manufacturers are known to use old lithium cells on new batteries. So when we get the new G1, the insides of the battery may be old and worn. Kinda like making a tasty stew with rotted meat. Stew looks great on the outside, but eat it and you are running to the toilet.
These smartphones are battery hogs anyway. With BT, WiFi, GPS, big displays, playing videos, games, and making phone calls, that's a heavy load on these little phones.
You need a BIG battery to handle these the processes you put the phone through, but manufacturers are torn between designing a HUGE phone with an adequate battery or slimming them down to make the phone attractive, but knowing the battery is too small for what the phone will be going through.
Look at my YouTube video. That extended battery bulked up the phone, but it now has the size battery needed for the G1.
Consider yourself lucky. Poor Apple stuck its iPhone users with a non-removable battery. That was one of the reasons I was not interested i that phone.
And I hear lots of iPhone users complaining about the iPhone's inadequate battery! But they are stuck. While a competent geek can replace the battery, 90% of iPhone users don't have a clue how to replace the battery themselves.