The testing version of Google Talk has been updated to include voicemail, file transfers and music status -- three features that were much needed. In particular, the voicemail feature has been in the rumor mill since February, and it's good to see it has finally arrived. You can read about these new features on the "what's new" page for Google Talk.
When sending a voicemail to someone, you are greeted with a message that says in an english accent: "The person you are trying to reach isn't available, please leave a message after the meep... MEEEEEP". There is no sign that you can customize that message, but it would definitely be something they should look into.
To listen to a message, you can find them in your Gmail. The subject says "Voicemail from Garett Rogers (8 seconds)", and when you click on the message it displays a play button and progress bar -- similar to the one associated with videos on Google Video.
Sending files is simple too -- if a contact has this latest version, a new button appears on their active chat windows that says "Send Files". According to the page about this feature, there is no restriction to the type of file that can be sent and should work from behind firewalls (although transfer speeds may be slower than expected in this situation).
And last, but not least, the music status almost seems too easy -- to have the title of the music you are listening to appear, you just have to select it in the dropdown that contains your availability statuses. Once you have done this, it is smart enough to know which music player is playing audio, then it will display the title in your status box.
The file transfer feature is one that has been requested since the day Google Talk was launched -- it could definitely help the adoption rate of this product.