Do you use live wallpapers? Do you have automatic brightness turned on? High battery using applications running?

I've never had an issue regarding battery problems with Launcher Pro. In the settings you can click on Memory Usage settings which could possibly help. Tweak those , end all applications and go from there.
Automatic Brightness is turned on - but always has been. I've been thinking on this; because in the last two weeks my phone has gone from once a day charge to twice a day. I'm not using Live Wallpapers - I just have a picture as my wallpaper but did have picture widgets when I was using Launcher Pro. Other than that, recent changes are the SMS backup - which I changed from autobackup to manual and only run that once a day. I did have the Caller Info app installed but uninstalled that (which helped a little). I also recently started using the default email app for my other email accounts.
I checked the "Battery Use" and the only thing I noticed out of the ordinary today is "wpa_supplicant" which I don't remember seeing before but I googled that and it is for WPA security and all the wireless WiFi networks I connect to have security so I'm thinking I never noticed that before.
You know, this is unfortunate about the Nexus One. My Li-ion battery is still going strong. The problem is that some Li-ions last a long time and some don't.

If you think Launcher Pro is the nuisance behind it, then re-install it. Save your settings and homescreen within Launcher Pro itself before reinstalling. I have photo widgets on two of my screens and I havent had an issue.

I did a battery pull when I was having issues and I fully charged it and never had an issue since. Hopefully that helps you!