Plant Sense, a start up announced in 2006, is just entering public beta testing of its GardenGro Sensor. Think of it as Nike+ for your plants. After connecting the sensor to your computer and telling it whether you want to monitor an existing plant or analyze soil for a new plant, place the sensor (pictured above) in the soil/next to the plant for 24 hours. Remove the USB part of the sensor and connect it to your computer. The data (which includes moisture, light and soil composition among others) is sent to Plant Sense where it is analyzed, and you receive all the information you could want about the health of your plant or the ideal plant for the soil conditions it has monitored.
Beta test kits currently available for $60, which is the expected price of the GardenGro Sensor and initial subscription to the Plant Sense service. Launch seems to be set for Fall 2008.
via Silicon Valley, an article with details about the history of the company, founders, and their recent venture funding.