Phone Amego is new utility that integrates your Mac with iPhone (or other Bluetooth phones) and Google Voice. I'm especially interested in its ability to trigger scripts based on a device's proximity. This means it could be used to provide the solutions described in Your Mac Knows When You're Home.
There's every indication that Phone Amego, despite the illiterate spelling, will be a solid application too. It's from Sustainable Softworks, makers of many fine network related Mac tools.
For an overview of Phone Amego, see TidBITS iPod & iPhone: The Macintosh/iPhone Mind Meld.