Two new little Google Voice features just made their way into Gmail. A new option lets text messages sent to Google Voice show up as e-mail messages in Gmail. You can reply to messages from Gmail, too, which makes it a nice platform for carrying on a text message conversation.
Also, there's a new Labs feature in Gmail that lets you play your Google Voice voicemail messages from inside the Gmail viewer. Previously, Gmail would send you the text transcript of your message, but if you wanted to play the audio file, it would open a new browser window to do so.
Small snags: Although the features are thematically linked, they're enabled differently. The SMS feature is turned on within the Settings tab of Google Voice; the Gmail voicemail player needs to be enabled from withing the Labs tab of Gmail. Also, while receiving and replying to Google Voice SMS messages in Gmail is now easy, I didn't see how one could initiate a Google Voice SMS conversation from within Gmail even with the SMS feature turned on.
I like where this is going. I'm still not a huge fan of the Gmail user interface, but it's great to be able to see and manage e-mails, voicemails, and SMS messages all in one place. It will be interesting to see if Google Wave gets similar Universal Inbox features.