final version of 1.5.1 is here. The core team and dozens of contributors have fixed 30 bugs and introduced a slew of features and performance optimizations since 1.5.0. Here’s a look at the highlights of our best release yet.

• Incredible Selector speedup and full CSS3 support (read about it in the original post).
• Full JSON encoding and decoding support and options for improved security.
• Optimized Element#get/setStyle for cross-browser compatibility and speed.
• Various String method enhancements and fixes.
• The new Form#request method simplifies the common case of submitting a serialized form with XMLHttpRequest.
• Many form serialization fixes—if you had troubles before, now they’ve been squashed

Api docs here: the API documentation.