Want to know if your friends are at their desk or out and about on their Android phone? This is a tip for you.
The more friends you have signed up to Gmail, or any Google product, the more chance you'll be using a little Google Chat now and then. When you're checking in on who is available online in Gmail, there's a Google Labs setting that will also let you know which friends are currently active via their Android phone.
Go to Settings, then Labs, then look for Green Robot! Enable this option and you'll now see any friends who are using an Android phone appear as a little robot icon instead of the boring old circle.