Google Voice with your existing number - how about building a trapcall type service?

Google Voice Blog: Google Voice with your existing number

Now you can use google voice with your existing number and still use features such as visual voice mail etc... I wonder if Google will set up a service such as trap call (or even buy it)? that way, an user can transfer a call to Google Voice... for recording etc..and may even be able to set it up to be transferred elsewhere based on the rules that they may have setup.