Two surveys released yesterday show that interest in Apple's iPhone is holding steady, despite competition from BlackBerry vendor Research in Motion and Palm, maker of the Treo and forthcoming Pre smartphones. In its biannual survey on teens, Piper Jaffray found that the iPhone remains popular with U.S. teens, although it's not as hot as it was when the iPhone 3G launched last summer amid nationwide hoopla. Nevertheless, 16 percent of survey respondents still plan to buy an iPhone in the next six months. Meanwhile, ChangeWave Research reports that its survey of adult cell phone owners shows that 37 percent plan to buy a BlackBerry in the next six months and 30 percent plan to buy an iPhone. Only 4 percent plan to buy a Palm. Article