Sproutsheet is taking a new direction going from a website + web application to a web application that stores your data locally. The website will be used to promote the new application and the old website is moved to http://old.sproutsheet.com.
For more information about the new application make sure to read: the new application or the about page.
Your data is still available on the old website. I am thinking of adding an export feature to the old application that will let you import your data inside the new application. Most of the code already exists, but since the old app doesn't really map nicely to the new app I am a little hesitant to implement it.
If you have a suggestion or an opinion about this feel free to start a conversation on the forum.
If you posted links to your grows on your website or community forum these links will continue to work. For example, http://sproutsheet.com/grows/1 will redirect to http://old.sproutsheet.com/grows/1. I'll keep doing this until I notice no more incoming links to the old urls.
I encourage everybody to switch to the new application. Registrations are disabled so no new users can be created on the old website, but old users can still login.