Google Voice received its first major update in some time earlier today, undergoing a major UI refresh for Android 4.0 Ice Cream Sandwich devices (Gingerbread devices only see minor changes, such as the app icon), as well as new interface for Honeycomb and ICS tablets. Under the hood, SMS offline message queuing is now supported and works for multiple recipients.
Unfortunately, it still is ungodly slow to load on my Gingerbread phone, and scrolls like something from Android 1.6. I hear it's a lot smoother on Ice Cream Sandwich, though. Hit up the Market to download it now.