I give my GV # to everyone. It rings my work phone during business hours, my google talk account when I'm logged in to that, and my company-issue cell all the time. My cell is forwarded to GV for voicemail in case someone calls me with that number directly. I changed phones, carriers, and cell numbers recently and it was easy - I just logged into GV, deleted the old number, added the new one in, and followed Google's instructions to forward my VZ phone to GV Voicemail. No long list of people to notify.