By now you've probably heard about the fact that Orbitz users accessing the site via Macs are seeing more expensive hotel options when they search. But it seems worth clearing up a couple of fallacies.
First, it's not as if the same hotel room is being offered at a higher prices to Mac users. (So no, using Windows to access Orbitz won't get you a better deal.) Orbitz offers the same search results to Windows and Mac users, but Mac users may see more expensive hotels higher earlier in the search results.
And the reason why this is happening isn't segmentation, as some have claimed. From what I remember of the Orbitz presentation at the R user conference a couple of years ago, all sorts of signals go into the R model to try and predict which hotels a given Orbitz user might be interested in: WebTrends data, search history, purchase history, planned travel dates … and the user's browser and operating system. It would seem that the browser (perhaps Safari / iOS) and/or the operating system is a strong signal that the user is likely to purchase a higher-priced hotel room. The Orbitz system (as I understand it) is designed to rank search results showing the results the specific user is most likely to be interested in at the top of the list. If Mac users, on average, spend more on hotel rooms than other Orbitz visitors, then it's not surprising that more expensive results would appear at the top of the list.
But it's not as if Mac users being singled out for special treatment. Segmentation is a marketing operation (and a conscious decision), whereas the use of signals like these is part of a predictive analytics operation (driven by data, not people). It's important to understand the distinction.
You can read more about how Orbitz uses R and Hadoop to drive its search at the link below.