Let’s Encrypt will enter Public Beta on December 3, 2015. Once we’ve entered Public Beta our systems will be open to anyone who would like to request a certificate. There will no longer be a requirement to sign up and wait for an invitation.
Our Limited Beta started on September 12, 2015. We’ve issued over 11,000 certificates since then, and this operational experience has given us confidence that our systems are ready for an open Public Beta.
It’s time for the Web to take a big step forward in terms of security and privacy. We want to see HTTPS become the default. Let’s Encrypt was built to enable that by making it as easy as possible to get and manage certificates.
We have more work to do before we’re comfortable dropping the beta label entirely, particularly on the client experience. Automation is a cornerstone of our strategy, and we need to make sure that the client works smoothly and reliably on a wide range of platforms. We’ll be monitoring feedback from users closely, and making improvements as quickly as possible.
Let’s Encrypt depends on support from a wide variety of individuals and organizations. Please consider getting involved, and if your company or organization would like to sponsor Let’s Encrypt please email us at sponsor@letsencrypt.org.

from https://letsencrypt.org/2015/11/12/public-beta-timing.html