Google Talk does not provide a built-in functionality to allow you to control your idle status.
There are probably times when you’d rather not let people know you are around. gAlwaysIdle allows you update your status to ‘always idle’ so you appear away even when you are typing e-mails and sending instant messages.
Similar to ‘always idle’, it lets you update your status to ‘never idle’ when you are away from your computer.
You can download the software from the following link.
Download G Always Idle
gAlways Idle website is down and it only shows the Apache web server homepage now. Its difficult to find that software on net too…