[email protected] for a little over a year and their capabilities are mind blowing. No longer are you tied to a proprietary phone system and the hardware base of the switch vendors. You are free to setup forwarding, linking and automated scripts to your heart's content. This system is not for the faint of heart, but chances are that you have a no-longer-used, sub-gigahertz PC at your feet below and have just the amount of curiosity that it takes to tinker with one of the most powerful telephony applications on the planet. I'm only upset that the bugs that were fixed in [email protected] didn't make it into the 1.0 and even the 1.1 version of TrixBox. If you can; go with an @Home distribution with FreePBX until 1.2 gets rid of these silly daemons.
More info on setting up your own Asterisk box can be found in my PC Magazine story here: Your Virtual Assistant.