Nest has been busy throughout the night and into this morning, attempting to address service outage affecting owners of the Nest Thermostat and Dropcams. The issue impacted Nest web and mobile apps, making it impossible for many to remotely access said hardware.
The company is well aware of the issue affecting customers and has worked to resolve the problem:
Nest service has been restored. We'll continue to monitor the situation and will take immediate steps if any additional incidents occur.— Nest Support (@nestsupport) September 8, 2015
If you happen to still be out of luck, it's recommend you get in touch with Nest to see what they can do to assist. Be sure to check out the Nest status page for more details should you encounter issues further down the road.