It's not just all about the battery! Battery tech has improved drastically over the past few years. I still remember having to carefully discharge the early Nokias which had NiCad. Then NiMH became mainstream and phones would last for days on end.
Now try and imagine what did those batteries back then have to power? A tiny black and white LCD, no GPRS, no MP3 player. My first colour phone was a Nokia 3510 and it's battery lasted only a day (as a result of heavy snake II playing, in COLOUR! Lol).
Now step forwards ~10 years and what do the latest LiPO/Li-ion batteries have to power? Massive 3-inch + Hi-Res brightly backlit screens, HSDPA, 1 Ghz + CPUs, 3D GPUs, WiFi, Bluetooth, video playback, music playback.... You get the picture!! So no, a comparison back to days of old is not substantiated.
Cellphone technology has just moved too fast for battery tech! Like it has been mentioned in this thread, phones like the iPhone last quite a bit longer than most other brands and I think this is purely because of well engineered circuitry.