Over at Ars Technica, I saw the article Mobile phone users love their pornography. Yes they do, but we already knew that. Ars said this also, regarding the disparity between phones and PDAs:

One of the study's more intriguing findings concern is the relative virtue of PDA users. While 20 percent of mobile phone queries are for adult material, only five percent of PDA searches are for porn. Despite the larger screen, PDAs are apparently not mobile porn platforms. The authors chalk this up to the "business-oriented use cases of these devices" and the "potentially different demographic of users" (read: fewer 17-year-old boys own a PDA).

That may be, but there's probably a simpler explanation: text input method. Sorry to be gross. But beyond this specific topic, I think this is useful research on how device input format has a direct and measurable impact on search and browsing behavior. Are you more likely to tap out a search with a stylus or T9 it with a keypad? Remember, this study was about searching, not browsing. But for selecting links on a page, a stylus beats a joystick any day as long as you can devote two hands to the task. OK, ewww. This post is done now.