Some Google Voice users noticed a feature that appeared in their accounts called Number Porting. This means adding your existing number to Google Voice, as opposed to having to use a new phone number entirely for the service, which users have had to do up until this point. The feature is evidently only being tested for the time being, but will could go mainstream in the future. If you don't have to get a new number, there's a much bigger incentive to use Google Voice...that is if you don't mind paying the price.