Import Verizon Contacts to Google Voice using Backup Assistant.

Get Backup Assistant

1. Select Get GOING or Media Center (some newer phones go to Tools On The Go or Browse and Download.)
2. Select Business/Tools.
3. Find Backup Assistant.
4. Download it to your phone.

as per http://support.vzw.com/faqs/Get%20It%20Now/faq_backupassistant.html#item2
You may have to subscribe to it for $1.99, you may get it for free. Either way,  do it! You can cancel it tomorrow. You only need it once.

Get your contacts in CSV

1. Let BA sync at least once
   (should happen when you install it. If not, it happens twice a day)
2. Login to http://www.verizon.com
3. My Services (top right)
4. My Contacts (middle left)
5. Export to CSV (middle right next to contact search bar)

Import to Google Voice

1. Login to Google Voice
2. Contacts (middle left)
3. Import (upper right)
4. Select the CSV (no modifications necessary)
5. My Contacts (upper middle)
6. Find Duplicates (lower middle right)

Now you're done!

Notify all of your friends that you're using GV and give them your new number.

(406) XXX-XXXX What?

Google uses a scoped 406 number for each of your contacts. 

Have a friend text you and notice that you get two numbers: one is google's 406 id for that person in your contact list. The other is their number.

What that means is that you can call or sms (text) the person from any of your Google Voice registered phones with that 406 number, but not from someone else's phone. Use this as the Mobile 2 number for your contacts and when you call them on Mobile 2 your GV number will appear on their caller ID.

P.S. I may be lying about the scoped number, I made that part up. I don't have any research to back it up, but it makes sense so I assume it's true until someone tells me otherwise.