Your chances of having the first one on the block: High, given the level of effort they take to put together and the fact that the Twitter version has been available for just a few months.
What you must know: These kits really do require assembly, down to the level of soldering on the components and tweaking the software code that determines how much water your plant needs, so you have to be an electronics geek to get them to work. The has the complete instructions, complete with photos. If you're particularly savvy, you'll figure out how to establish a wireless connection so that you don't need to run cables to all your plants.
What you need: You'll need basic tools such as screwdrivers and pliers, as well as a soldering iron and solder. A kit costs $100.