Early Apple Macs did have a default standard screen gamma of 1.8, but Apple abandoned that almost 10 years ago for the now almost universal 2.2 screen gamma. However I would expect you will find some graphics and pre-press processors working on documents that will go on offset presses still adhere to the 1.8 gamma standard, as they also stick with the D50 color standard rather than the D65 standard now supported by all of the major players like Apple, Microsoft and Adobe.

To obtain effective color managed print matching, and especially optimum display performance with an LCD it is probably wise to conform to the current industry standards of gamma 2.2 and color temperature D65.

You can obtain more technical and detailed discussion of the reasons and effects of these standards by going to the web sites of the major companies offering color management products like Gretag-Macbeth and ColorVision as well as the information site of Chromix.com - URL: http://www.colorwiki.com/wiki/ColorWiki_Home

This is from Mastering Digital Black and White by Amadou Diallo:

>>Common wisdom has it that this gamma was a closer match to the output of its Laser Writer printers. Remember those? This fudge was an early attempt to match the monitor to the print, without benefit of soft proofing and other color management tools.