Nest Labs, a company created by two former Apple executives, unveiled the Nest Learning Thermostat just over two years ago. We had a hunch that the device would be a hit as it sold out almost immediately and remained out of stock for several months. Now thanks to an exclusive report from GigaOm, we have an idea of just how successful the learning thermostat really is.

Sources told the publication that the startup is now shipping 40,000 to 50,000 thermostats each month. At the current growth rate, they could very well ship in excess of 1 million units each year by this summer. Keep in mind that we are talking shipments, not sales – but even still, that’s extremely impressive for a device that’s billed by many as little more than a luxury item for techies.

The company has struck up a number of partnerships in the US, including a deal with Apple to sell the thermostat in Apple’s online store as well as at big box retailers like Best Buy and Lowe’s. Service providers like Reliant are also getting in on the action and according to the sources, Nest is doing very well in Europe as well.

The startup just closed on a new round of funding valued at $80 million following a post-money valuation of $800 million. We are hearing that Google Ventures led this round of funding, joining others like Kleiner Perkins, Generation Capital, Lightspeed Venture partners and Shasta Ventures.