Apple is set to launch the biggest ever update to its Mac line-up at the conmpany's Worldwide Developer Conference (WWDC) which kicks off in San Francisco on Monday, 11 June.

Apple WWDC 2012

Apple is already decorating the Moscone West centre in San Francisco for WWDC 2012 and Tim Cook, Apple's CEO is set to make some pretty major announcements when he takes the stage on Monday.

We already know that Apple will officially launch the latest version of its desktop software, Mac OS X Mountain Lion, as well as the probability of launching iOS 6 and a major update to iCloud, though it is not expected that it will announce any iOS hardware, such as a new iPod or iPhone, saving those announcements for the autumn.

However, according to sources who spoke to 9to5Mac, Apple is readying its biggest ever Mac refresh and will launch new models in four of its five Mac ranges, leaving only the Mac Mini as it is.

The major update to both the laptop ranges and the iMac is expected to be the addition of Retina Displays. We already reported on the rumours that Apple was prepping redesigned MacBook Pros with slimmer profiles as well as the super high resolution displays.

Another new feature will be the addition of USB 3.0, which for some will be a surprise move, considering Apple had gone for Thunderbolt connections on its previous MacBook Pro models. According to the prototypes seen by sources, the USB 3.0 ports will sit alongside Thunderbolt ports rather than replace them.

Retina Display MacBook Airs

Retina Display MacBook Airs

Appl'es MacBook Airs have set the standard for a slew of Ultrabooks from a range of manufacturers in the last 12 months, however Apple still sets the standard. Slimming down these ultraportable laptops any more is unlikely and with the design already seen as a classic, it is unlikely that Apple will tinker with the overall look of the 11.6in and 13.3in Airs. However it is planning on making one major upgrade to the line-up.

According to 9to5Mac sources, Apple will be rolling out the Retina Displays to this set of laptops too, making two versions of the 11.6in and 13.3in laptops, one with the upgraded display and one without.

It is unclear yet whether USB 3.0 ports will make an appearance on the new Air models, though many consumers will be hoping they do, as USB 3.0 peripherals are becoming very popular.

The final Mac line to get the Retina treatment is reported to be the iMacs. High resolution iMac panels have reportedly been spotted in the supply chain making these iconic desktops even more appealing.

Lastly, Apple is set to update its professional desktop range, the Mac Pro, making it available in three configurations including one with OS X Server capabilities. We also expect to see Thunderbolt and USB 3.0 connections added as well as a variety of Intel's latest Xeon E5 chips and the latest graphics chips.

Apple hasn't updated it Mac Pro line-up since July 2010 so this could be a fairly major refresh, putting pay to earlier reports that Apple was planning to do away with the Mac Pro range.

WWDC kicks off on Monday, June 11 with the exact timing of the keynote speech by Tim Cook, when we expect to see all this new hardware, is yet to be announced. IBTimes UK will however be on hand to make sure you don't miss a thing with live coverage of the event.