Here's a link to the Nest blog post discussing the acquisition:
Nest has raised in excess of $80 million and was rumored to be raising a $150 million round led by DST Global that would value Nest at $2 billion. Venture capital fund investors in Nest include Kleiner Perkins Caufield & Byers, Lightspeed Venture Partners, Shasta Ventues, Venrock and Generation Investment Management. Google Ventures was also an investor in Nest.
Here's a link to Dan Primack's article on Fortune.com about the acquisition: