Numerous reports/ rumors have sprung up recently on what Apple is expected to announce this WWDC next Monday, ranging from iMacs, Mac Pros and of course different versions of Macbooks (Pros, Retinas and Airs). All the current Macbooks have the uni-body design introduced in 2008, while this design is amazing in all aspects from mobility to durability, it is kind of half a decade old and improvements are certainly due. Also almost 100% certain now is that these computers will have the Intel's new 4th generation processors called Haswal, that is supposed to be much better in power handling and speed bumps (of course). So this improvement in power management along with Apple's OS 10 should imply a beast in terms of battery life (look at what these processors can do even with Windows that is traditionally careless with its power management and has almost insignificant battery life compared to the Apple computer).
Other than this nothing else is certain, except for some leaked product SKUs and inferences from Tim Cook's email and phone conversations with Apple Product Managers, that suggest new Mac Pros/ Retina Airs / totally redesigned Macbooks. Hence other than the odd confirmation from Tim Cook himself at the D11 conference, that iOS 7 and OS 10.9 will be showcased in WWDC on June 10th, nothing is certain and yeah it surely does feel like 'the Christmas eve' Mr. Cook!