I just got my Palm Pre 2 on Verizon and I was about to throw it out a window. I couldn't get my Exchange email to sync or even create the account. It kept saying my password was incorrect. I'm actually the Sysadmin for my company so I knew the password was correct and I knew the settings were correct. I finally figured out what was wrong! My account in Active Directory was setup incorrectly. This fix may not do it for some people but it really helped me.
Here is the link to the article I used Activesync Working But Only For Some Users On Exchange 2007 / 2010 « Alan Hardisty's Blog – All Things IT Related
You basically have to enable inheritable permissions for your account in AD, which I hadn't enabled on my own account for some reason.
I hope this helps someone else, because I was really in a pickle until I found this.