latest jquery 1.4.2 downloaded from jquery.com comes with Sizzle.js also.
How and what benefit can I take from included Sizzle.js?
Is Sizzle.js a standalone lib
Sizzle.js is a JavaScript library that implements a "CSS selector engine designed to be easily dropped in to a host library." jQuery uses it internally for its CSS selection needs. If you wanted a CSS engine and had no need for all the other JavaScript benefits of jQuery, you could use Sizzle.js separately.