I finally assembled a Tweet-a-Watt hack of the Kill-a-Watt power meter, which adds an Xbee chip transmitter, sending to a receiver on a laptop. In LadyAda's original tutorial, the data is sent to Google App Engine to provide web access and graphing. But I wanted to send it to Pachube.
Love the lazy web. Brian Naughton had already adapted the Python script to report to Pachube, and shared it with me. Now he has posted it.
UPDATE: I added back the Twitter code that Brian removed. So now there is a PachTweet-a-Watt version, that does both. It can be found here.