Google has announced that it will be integrating Google Voice with Sprint devices to give users a nearly native experience from their Google Voice number. The Android GV experience already is as good as it gets, and it's about to get better. The long and the short of it is that your Sprint number will become your Google Voice number, without any messy porting. Here are the deets, straight from the Google Voice blog:
First, Sprint customers will be able to use their existing Sprint mobile number as their Google Voice number and have it ring multiple other phones simultaneously. So now, calls to your Sprint mobile number can easily be answered from your office or your home phone, or even your computer through Gmail. Calls from Gmail and text messages sent from google.com/voice will also display your Sprint number. This basically gives Sprint customers all the benefits of Google Voice without the need to change or port their number.
Alternatively, Google Voice users can choose to replace their Sprint number with their Google Voice number when placing calls or sending text messages from their Sprint handset. This feature works on all Sprint phones and gives Sprint users all the benefits of Google Voice without the need for an app.
While unfortunately this is not currently available right now, it will be coming "soon" to all Sprint users. If you are a Sprint user, be sure to drop your email at this link to sign up for the service. [Google Voice Blog]