MacBook – How many monitors can the new retina MacBook Pro handle and at which pixels resolutions

There are all sorts of high end specialized displays that have this resolution for the medical, government imagery, and engineering markets.

http://en.wikipedia.org/wiki/Graphic_display_resolutions

You can see any Hyper XGA display exceeds 2880 by 1800 (but are not shipping as single monitors yet) and most Quad XGA displays (shipping since 2001) exceed the "15 inch retina" in terms of sheer pixels on one display panel/monitor.

Supported resolutions

• Retina, Ratio 16:10

  • 2880 by 1800 pixels

• scaled, Ratio 16:10

  • 1920 x 1200 pixels
  • 1680 x 1050 pixels
  • 1280 x 800 pixels
  • 1024 x 640 pixels

According to the official tech specs by Apple.

How does the scaling work?

According to an article in AnandTech:

Selecting any of these options gives you the effective desktop resolution of the setting, but Apple actually renders the screen at a higher resolution and scales it to fit the 2880 x 1800 panel. As a result of this scaled rendering, there can be a performance and quality impact.

There is a new option to configure the resolution in the system settings. While you actually change the resolution, Apple only refers to the visual impact of the settings.

So basically changing the resolution offers:

1. Large text, but much crisper.
2. More space for visual content (and smaller text), but not as sharp.
3. Something in-between (default retina).

(original picture from AnandTech)

Note:

Due to the imprecise definition of "retina display", this answer may seem confusing, because at the top Apple speaks of 2880x1800 as retina, but the picture suggest something different.