The December newsletter highlights the General Availability of Schedules, Temporal .NET SDK, and Python SDK's Workflow Update feature. It also mentions upcoming webinars and meetups in Melbourne, Mumbai, San Francisco, and Hyderabad. Additionally, it provides access to 2023 Replay Conference talks on YouTube and introduces new Temporal 102 courses in various SDK languages. The newsletter encourages feedback from the community through their Community Slack or Twitter account.