Google has updated their homemade instant messaging client, Google Talk, today. The most important feature addition is what I'd like to call smart file sharing. You can drag-and-drop files or folders to share with contacts. For example, if you wanted to share a large picture with someone you can drag it into the chat window and it will send them a small preview. If they want to save the full-size of the picture, they can then click download originals.
It's also important to note that the new GTalk executes file transfers with a direct connection to your contact's computer whenever possible; leaving latency at a minimum. Other additions include voicemail which is great for leaving a message to an offline colleague. Download the latest version for your PC.