Google Talk now allows you to send offline messages to all your Chat History enabled Gmail buddies.
This was one of the greatest feature which missed out of Google Talk earlier, we used to see error message “<email address> is offline and can’t receive messages right now” when sending message to someone who is not signed in, but not anymore.
Note: Offline Messages won’t work if your recipient hasn’t enabled chat history or if your in “off the record” mode
Thanks: Sankar Anand, Via Googling Google

wrote, on November 1st, 2006
Then it will never work for me
wrote, on November 1st, 2006
Ajay: Why not ?
wrote, on November 2nd, 2006
Ah, very good! Thank you for the heads-up Thilak!
wrote, on November 2nd, 2006
This truly is a good additional feature to the GTalk. It was one thing that was missed when compared to YIM.