Im gonna put together a quick list of stuff I think/hope we will see.
There has already been so much leaked about this, I wont go into too much detail, but 5mp camera w/ flash, 960x640 resolution, front-facing camera, A4 processor, video chat, multitasking, record HD video. Thats most of the known, well substantiated rumors, but im sure that Steve will have a few more tricks up his sleeve, cant wait to see what those are.
iPad OS 4.0
This was not part of the OS 4.0 press conference a few months ago, so its times that it gets some press here at WWDC.
This one seems to fall right inline with the new iPhone release. If the new iPhone is truly 960x640 then there will be 3 device resolutions developers will have to deal with. I suspect that some tools for resolution independence will be included so devs dont have to make the same app 3 times. If you throw in a Apple TV to the mix, that alone could add 2-3 more resolutions that devs need to worry about.
Could Apple add some support for HTML5 in xCode, or in some other tool. If they are serious about HTML5 they dont just want everyone using Adobe's Dreamweaver.
There are alot of rumors on this already, most of which seem pretty reasonable. I dont really have much to add, except that I think its pretty plausible to atleast demo an update to Safari at the WWDC. The browser is more and more becoming the platform of the future. Google clearly believes this to be true, since they doubled down on the browser as a platform at Google IO.
Bing will be a search option on the iPhone, but not the default.
Lots of big rumors were flying around, but It they have seemed to die down, mostly in part due to the answers Steve Jobs gave at the D8 conference. When asked about Apple TV he mainly talked about how hard it is to sell set top boxes to consumers, when cable companies give them away for free. If Steve truly believes this than why would he try to sell a set top box ? Good question, so this one is probably unlikely. But, it is still possible, and it seems a necessary move to compete with google.
They are gonna atleast talk about this, they do every year. It would be nice to see some more cloud integration, maybe tie it in more with mobile me ? We'll see
Apple Magic Trackpad
these rumors just leaked today, but it seems Apple is set to announce a giant trackpad with handwriting recognition. Its bluetooth which means it would be usable by desktops, laptops, iPads, and even iPhones. This is something ive been hoping for, and im glad that i waited on getting a magic mouse because a trackpad is really what i would rather have.
this one seems pretty likely, all of the iTunes store has recently gone online for preview/purchase, but not streaming. I think apple will close the gap on that today. Expect integration into existing first party apps from apple (iPod, iTunes).
Apple needs to do this, even if its just a stripped down version of premium. Apple just needs to have a presence on the cloud with some free services. MSFT and google both have extensive online offerings all available free. We all know about google, but MSFT has some very serious offerings as well - online office, sky drive 25gb storage, free email, calender, etc...
Mac Pro Upgrade
this one is due for an upgrade. It might not be a 'major announcement' but the conference is for devs, and the Mac Pro is really meant for devs and high end technical people so it would make sense to announce it in the keynote just to get a huge round of applause from all the attendees.
Macbook Air Upgrade
Put a 3g sim in there, lower the price, maybe upgrade the specs, and then you've got a computer that moves from a niche marketplace, to one that is a little more mainstream.
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