Definitely not normal. If I drain my battery completely it probably takes about 3 hours to fully charge if using the AC charger. If it's plugged into my computer via USB than it takes quite a bit longer. Only did that once so not exactly sure how much longer. I wonder if there's a particular app that's causing your battery to drain at such an extreme rate. Also, what is your display brightness set to? It's the display that seems to use the most juice. I usually have mine set at <25% and it still uses 80% of my battery. Also what is your screen timeout set to? Maybe you can shorten that.
Do you leave your WiFi on when there isn't WiFi available? I may be wrong but I think it may use more power if it's constantly searching for a network than when it's connected. Have you looked at Battery Use data to see what is using the juice? I'd check that to see if there is maybe some bad app you got running that's causing the problem. Also there's some issue with the Dialer staying running after making or receiving a call. But I'm not exactly sure how real the battery drain is from that. I've noticed that the Battery Use data reports it as close to 30% even when it's only run for a few seconds, but my battery isn't draining as fast as that would suggest.
I've had my Inspire for about a month now. After the "newness" of it all wore off and I just started using it as I normally would, I've been really surprised at how long my battery has been lasting. Granted I don't make or receive a lot of calls nor do I use it as a media player. Mostly texting and web browsing. But a full charge is lasting me close to two days! Today for example, I used it a bit more than usual tracking all the college football and US Open scores and quite a bit of web surfing. I'm at 14.5 hours on battery w/ 54% remaining. And this is just the stock ROM, OTA Gingerbread update, with WiFi & GPS on the entire time.
From what you describe happening there is definitely something wrong, either with the phone or perhaps just the battery itself. I'd recommend doing a factory reset and not reinstall all your apps immediately. If the battery drain still happens that quickly with no additional apps then you can go back to ATT and tell them to send you an new phone again. If the battery usage seems to be reasonable then maybe install one or two apps and use it for a while to see if the battery drains faster. If not, then install another app. Keep going until you notice a significant decrease in battery life. I know that's a major PITA but might be worth it to focus in on the problem.
Sorry I couldn't provide a more definite solution to your problem. Post back with an update on how you get this resolved.