Adobe Principal Scientist Lars Borg:

Macintosh, in 1984, introduced us to desktop publishing and to displays with shades of grays. Publishing at that time meant printing presses, and the dot gain of a typical press (then and now) corresponds to a gamma of 1.8. As color management was non-existent at the time (the first color management solutions did not appear until early 1990s, when color displays became more available), Apple’s pick of a 1.8 display gamma enabled the Macintosh displays to match the press.

In early 1990s, the TV industry developed the High-Definition TV capture standard known as ITU Recommendation 709, using a net gamma of around 2. Later, in 1996, IEC put forth a CRT-based display standard (sRGB) for the Web that would match the HDTV capture standard, having a net gamma of around 2.2. sRGB was slowly adopted first in the PC display market, next in the burgeoning digital camera market, and 2.2 became the dominant display gamma.

In my expeirnce, unless you’re designing newspaper pages, gamma 2.2 is far nicer for most uses.