An important note not mentioned in this announcement is that Claude 4's training cutoff date is March 2025, which is the latest of any recent model. (Gemini 2.5 has a cutoff of January 2025) https://docs.anthropic.com/en/docs/about-claude/models/overv...
Both Sonnet and Opus 4 say Joe Biden is president and claim their knowledge cutoff is "April 2024".