I wonder if battery life is the same but percentage is displaying differently. On this wiki page (towards the bottom) under 4.3.1 bug fixes it says "Changes the behaviour of the battery percentage".
For me, it seems that my battery drains faster since the last update. I can unplug my phone, play just one round or Words With Friends, and it goes down to 98%. Check my email, then it's down to 95%. This is all within about 5 minutes or less.
There's an active thread on another website about this issue. It affects my iPhone 4 (4.3.1) as well. Running noticeably warm/hot all the time, even when sleeping. Battery drops quickly. Phone seems "sluggish", even the slide-to-wake switch. Started with 4.3.0, continued with 4.3.1.
The other board suggesting doing a Reset Network Settings which seemed to help. I also went snooping around in my iPhone's Mail settings and spotted something unexpected. On one of my two IMAP Gmail accounts the Drafts and Deleted mailboxes had been switched from "Store on iPhone" to "Store on Server". I did not configure it this way and nobody else would be monkeying with that setting. So I wonder if the 4.3.0/.1 update changed these settings -- and now it's trying to sync gigabytes of Deleted crap from my Gmail archives? Not sure, but just a thought I hadn't heard before....