HTML 5 - what caught my eye(edit)
wrapagain. This is cool if you've got a text box that takes code listings (which I do).
inputelement supports: datetime|datetime-local|date|month|week|time|number|range|email|url - perfect for validation.
manifestattribute, lending more support to offline (web) apps.
striketag is being binned. The funny thing being all the blogs that use the tag to indicate a correction will, without an update (and if they're in standards mode), have the mistake plugged back in. Then again, the browsers will probably keep the tag.
nameattribute is being striped away from forms and the like (obviously not inputs elements). No more excuses IE.
getElementsByClassName. Need I say more?
classList. We will be able to use methods such as
toggle()to manipulate classes on elements. I can almost smell the library changes.