OK - so I'm a little frustrated at the "required" Google voice integration. If you are like me you want to keep your Google voice number AND your Sprint number and still have the Google voicemail integration. The Google voice app already installed tries to get you to pick which number you want to use. I want to use both so what I have found as a workaround is to install the Google voice app from the Market. It will replace the stock app and you can chose what you want to do without it "forcing" you to pick a number. i don't know if this has been posted elsewhere. I couldn't find any information on it. Loving the Nexus S btw 
