yesterday jQuery 1.3 has been released as stable.

Whats new?

• Sizzle: A sizzlin’ hot CSS selector engine.
• Live Events: Event delegation with a jQuery twist.
• jQuery Event Overhaul: Completely rewired to simplify event handling.
• HTML Injection Rewrite: Lightning-fast HTML appending.
• Offset Rewrite: Super-quick position calculation.
• No More Browser Sniffing: Using feature detection to help jQuery last for many more years to come.

read more on http://www.jquery.com