Topping the list of purported new features is Safari Reader, which will "will make web page reading easier by extracting and organising the text," reports 9to5Mac.
Bing is also set to make an appearance in version 5. This development, if you'll remember last week, is not real surprise given all the talk about the search engine joining the iPhone alongside Google search.
Rounding out the news are claims that Safari 5 will render Javacript "25% faster" so that the browser is more Chrome- and Opera-like. HTML5 support, unsurprisingly, is primed to get polished and improved.
So there are a few updates, yes, but what we do not see, again, is any indication that a Safari extensions API will be made available at WWDC or within Safari 5. Maybe that'll be "one more thing..."
I present to you the evidence, here: