Here’s a tip for folks having the “The username and password you entered was not correct” bug with google voice.
I found that after installing google voice on my droid x and trying to login to voice using a “different email address” that the application would tell me that I had the wrong username and password.
I stumbled onto a workaround: go to google voice in your phone’s browser and login there. Doing this allowed me to login to Google voice (in the browser). Then I reopened google voice and it automatically worked (bypassed that previous login screen) and took me into the setup procedures.