Cheerful Apple spokesman aficionado John Gruber talks about four tweets that, according to him, "may" indicate an incoming Apple hardware upgrade, perhaps the introduction of new Retina Display-level Macs or displays. Given his intimately wet relationship with Apple, you better listen up to his "wishful thinking".
The latest update — which was pulled by Cupertino after dreadful stability reports — includes some high definition cursors. Here you can see the new Mickey Mouse pointing finger icon, redrawn for high-density displays in Mac OS X 10.7.3, compared to the current one. Other new cursors include the Mickey Mouse grabbing hand icon and the old Nextstep camera, all of them re-rendered at super-high resolution.
Fanboy Número Uno thinks that these icons, coupled by reports of some Mac Minis booting into HiDPI mode after the 10.7.3 update, may indicate that "we may be on the cusp of Apple releasing HiDPI Mac displays and/or HiDPI MacBooks. I.e.: retina display Macs."
For those new to this party, HiDPI is a new resolution independent mode designed to offer ultra-sharp graphic elements without making them tiny on the screen. As a screen's pixel density increases, the elements on the screen become smaller and smaller using traditional a display mode. You can observe this effect if you have a very high resolution monitor.
With HiDPI things change: the absolute size of a screen object is kept the same no matter how many pixels per inch you have on the screen. If you keep the size and increase the number of pixels that define the object, then you make it a lot sharper but never physically smaller.