Seems the same to me.
I updated to 4.2 GM when it came out. This release, I just updated my OS, like an end-user would, so all the Apps and media stayed on my iPad.
I've been using 4.2 now for a few days, and battery life seems the same as 3.2. I'm not fooling around in multitasking to shut down any apps or disabling notifications or anything. Just using it the same way I did under 3.2.
For the earlier betas, I wiped the iPad and did a clean install with only the Apps I needed to test. (All Apps I wrote). So I really couldn't judge battery life.