I found a post in my Google Reader where a person listed his wish list, pointing to a Pocketables post called "Here's my Google Voice wishlist".
I honestly just have one point, and if I didn't work in a place with no cellphone access, I wouldn't have that one.
I want my Android phone to be able to make and receive Google Voice calls over WiFi. I can do that on my laptop. I could do it with Skype, but I don't have a Skype-In number and if I did, that still wouldn't be the number I give out everywhere. This would be the real lifesaver for me.
I get "Integration beyond Sprint" but as I use Sprint, it isn't a crucial issue for me. I barely use SMS and MMS, as it's hamstrung email, but I get why some would want GVoice to do MMS as well, but it isn't a seller to me.
I scratch that. Being able to upload my voicemail greeting would be wonderful, too.