OpenAI DevDay: Opening keynote takeaways

ChatGPT:

Now you can custom your own ChatGPT by GPT Builder with prompt, instruction, profile avatar, conversation-starting, and inductive knowledge.
You can share your customized chatbot on the GPT store, and earn money when people use it.
ChatGPT now chooses the response model automatically, no more model picker menu.

API:

New model GPT-4 Turbo with 128k context length (~300 pages of a book). It's 2x token generation speed and less expensive (3x less for input tokens, 2x less for output tokens) than the current GPT-4.
The knowledge of GPT-4 Turbo is up to April 2023 (continuous improvement). It now supports JSON response (more output control).
New assistants API for Threading (now the API is aware of the conversation context, doesn't need to send from client-side anymore), Code Interpreter, Retrieva, and Function calling.
GPT-4 fine-tuning experimental access.
Copyright shield: OpenAI pays if you face legal claims around copyright infringement. This applies to generally available features of ChatGPT Enterprise and the developer platform.

New Models:

New DALL-E 3.
GPT-4 Turbo comes with vision capabilities.
New TTS API (with 6 unique voices) and Whisper 3 for text-to-speech are coming soon.