The Current Cost (CC) people have been talking about this IAM unit for ages ... and now, it's finally here. It works in conjunction with an existing CC receiver (not the Classic model) and lets you track power use at a 'device' level.
This is handy if you want to gain an insight into which appliances around your home are burning the most power. Yes, you can already buy devices that allow you to do this (they usually have a little LCD display that shows the number of kW hrs consumed e.g. Plug-In Power and Energy Monitor
), but the CC solution feeds all the data back to a central location. This means that you don't have to crawl about trying to read the LCD displays.
However, the IAM comes into its own when combined with a Home Automation system. I've been using these with a homeautomationhub to feed my power usage to the online graphing service at pachube. Can also get an SMS alert if a heater has been left switched on for too long.
Would have given this item a 5 star rating, but I found the transmission/reception range to be somewhat limited. As with many RF devices, your mileage will vary. Careful positioning of the receiver helps.
In summary, if you already have a Current Cost electricity monitor, these are a good add-on purchase.