I love Google Voice integration on the android. Though MMS messaging is still lacking, the feature-set pretty much rocks.
So, what is my wish? For Google Voice to be smart enough to manage all my messaging, not just the ones inbound to my GVoice number.
It would be awesome to have one app to text/call from (and, sync with voice.google.com so I can text/call online, too) and have it be smart enough to know what phone number to display to the recipient.
If the application took my inbound calls and texts from people calling/texting my normal cell number, receive them in Google Voice (and sync with my online account, too) and let me answer, collect voicemail, or receive/reply to texts either on my phone or online or have them bounce to another phone in my GoogleVoice settings.
WIN: This would ease the transition from people needing to tell everyone their new Google Voice number when they want to begin switching to the one-inbox goodness that is GV. Just install the app on your phone, connect to your Google Account and suddenly your phone and online accounts are connected easily and seamlessly!
WIN: This would tie people into their Google Accounts even more, encouraging calls from gMail and other online conversations to happen without people being tied to their phones.
Bonus: Have Google Voice insert a signature at the end of texts to someone’s handset number that says “Try calls/texts to my GoogleVoice number: 111-222-3333 http://voice.google.com”