Instant messaging – Chat with all of your Google Talk and Gmail contacts in real time.
Free PC-to-PC voice chat – You can talk to anyone else for free who’s online and has the Google Talk client.
Send and receive voicemails – If the person you’re calling isn’t available, you can leave a voicemail.
Unlimited file transfers – Send files to your contacts. There are no file size or bandwidth restrictions.
Gmail notifications on your desktop – When you’re signed into Google Talk, you’ll be notified of new messages in your Gmail inbox.