I've just upgraded my website to jQuery 1.3. First thing that broke was the attribute selector. This was well documented in the jQuery 1.3 Release Notes - Upgrading as well as in the documentation. So this was easily fixed.
Another problem I had was with a selector matching <select> tags, such as
For some reason it is no longer matching the <select> tag, but it's <option> tags instead. There is plenty of buzz about how jQuery switched to Sizzle.js selector engine and all the performance gains. I have not found any information pointing to the change that causes by selector bug. Navigating to the parent node solved the issue for me, but it's more like an ugly hack rather than expected behavior.
Anybody else noticed this problem?