It's been a while since Apple's WWDC keynotes have focused on Mac hardware — recent years have been primarily dedicated to iOS, the iPhone, and (to a lesser extent) OS X. However, if a 9to5Mac report is to believed, that's going to change this year. The latest rumor claims that nearly the entire Mac lineup will be turned over, with the MacBook Air, MacBook Pro, and iMac lines receiving updates; the report also claims that either the Mac Pro or Mac Mini line will be updated, though it's not yet certain which computer will see updates.
The biggest bit of new info is probably surrounding the MacBook Air — the word is that both the 11-inch and 13-inch computers will be upgraded to retina displays, though in this context, it's not clear what exactly that resolution will be. We've heard lately that Sharp's working on new display technology with extremely high resolutions, including a 13.5-inch screen with a 3840 x 2160 resolution, so a MacBook Air with a retina display isn't an impossibility. 9to5Mac also reiterated its earlier rumor regarding a new 15-inch MacBook Pro with a retina display, USB 3.0, and a thinner profile.
As for the iMac, Mac Mini, and Mac Pro, details were less concrete. The iMac may or may not come with a retina-class display, while it's not clear yet which of the Mac Mini and Mac Pro will be updated. Last, but not least, Apple may also be refreshing its line of accessories, including keyboards, mice, trackpads, or Airport wireless products — but again, there's no concrete details yet.
While Apple refreshing this many of its computers all at once would be somewhat unprecedented, it also seems like a necessary move at this point — most of the company's major computer lines are nearly a year old at this point, and there's a lot of new technology (particularly Ivy Bridge) that would provide a nice boost to Apple's lineup. The Mac Pro, in particular, hasn't been updated in almost two years — if the company plans to keep the tower around, now would be a great time to give it an update. There's also the matter of Mountain Lion, which is drawing close to release — having a whole new hardware lineup to go along with the refreshed OS would certainly help back up Tim Cook's plans for a big 2012.