Apple last week released Apple Remote Desktop 3.1, making the company's remote control and management application into a universal binary and fixing numerous bugs and limitations [1] that you can read more about on Apple's Web site. The main new capability in Remote Desktop 3.1 is support for "lights-out management [2]," which enables a system administrator to monitor and manage a remote server whether or not the machine is powered on. Lights-out management is a new feature of the Intel-based Xserves, so if you're managing one of those machines with Remote Desktop 3.1, you can turn it on if it's off, even via AppleScript; all that's necessary is an Ethernet connection. (According to a post on the Ars Technica Infinite Loop journal [3], the Intel-based Xserve uses nearly all of the IPMI 2.0 specification [4], meaning that third party solutions will also be able to manage the Xserve remotely.) Apple Remote Desktop 3.1 is a free update for owners of version 3.0, and although the admin comes with a matching 3.1 client that's presumably necessary for the new lights-out management features, Remote Desktop 3.1 Admin can still control older versions of the client. The admin is a 28 MB download [5]; the client is a 2.5 download [6], available from Apple Downloads and from Software Update.

[1]: http://docs.info.apple.com/article.html?artnum=304569
[2]: http://en.wikipedia.org/wiki/Lights_out_management
[3]: http://origin.arstechnica.com/journals/apple.ars/2006/10/27/5773
[4]: http://en.wikipedia.org/wiki/IPMI
[5]: http://www.apple.com/support/downloads/appleremotedesktop31admin.html
[6]: http://www.apple.com/support/downloads/appleremotedesktop31client.html