Week from May 11 to May 24 (before r44117). To test those changes, you'll need a WebKit nightly.
New input types (43267)
4 new input fields are now supported : url, mail, number et tel (see the HTML5 spec). No additional functionality (like completion with the address book, the bookmarks, etc), just a basic support. But we can guess those functionalities will be available later.
ARIA role : grid(43669)
Even if Safari 4 has a basic support of WAI-ARIA, the work is not over. New roles are still coming in.
Orientation and ratio available in CSS (43739)
Media queries in CSS give a better control through knowledge of the properties of the device. WebKit already supports some of those queries. This change adds support for orientation (portrait or landscape) and ration (exact, minimal or maximal) of the view.
displayName support in the debugger (43774)
Anonymous functions are often used in JavaScript. They are really handy for development but not so much when you have to find where a problem lies. Therefore, Francisco Tolmasky of 280North got the idea of the function.displayName property. You can now choose what name the debugger will use. Before that, he has also done a similar change for the profiler. I can only recommend the lengthy article he wrote about it.
This is everything for this week. Of course, this is just a selection I've made. If you've noticed any other interesting changes, please let me know. Same thing if I got something wrong.