OpenAI has released two new models, o1-preview and o1-mini, which are designed to improve reasoning capabilities through a chain-of-thought approach. These models use reinforcement learning to refine their strategies and can handle more complicated prompts. The models introduce new trade-offs in terms of cost and performance, with longer response times and higher token usage. The o1 models are currently only available to tier 5 accounts and have limitations such as no system prompt support and no streaming support.