It appears iPad users are marking content during the day and consuming it later when they can lean back and actually read. According to Read it Later (@readitlater), from a study of 100 million articles saved using its service, people use browsing and bookmarking to time-shift the consumption of content to whatever would be prime time for them (typically 6am breakfast, 9am commute, 5-6pm commute, or 8-10pm couch time, the latter being the most prevalent).
When a reader is given a choice about how to consume their content, a major shift in behavior occurs. They no longer consume the majority of their content during the day, on their computer. Instead they shift that content to prime time and onto a device better suited for consumption.
Initially, it appears that the devices users prefer for reading are mobile devices, most notably the iPad. It’s the iPad leading the jailbreak from consuming content in our desk chairs.