XM Satellite Radio will begin shipping XM-enabled portable MP3 players (the Helix from Samsung and Inno from Pioneer) that not only offer recording and time-shifting but also have a button that users can push to "bookmark" songs playing on the radio - and then automatically buy and download them from Napster when the players are docked to an internet-connected port, writes AdAge. And that the "push-and-purchase" function may soon be made available for advertising.

"The next generation will be that if you want to hit that button for more information about that product you just heard described," D. Scott Karnedy, SVP of ad sales at XM is quoted as having said at a radio panel last week.

"Typically you don't think of radio as being the best direct-response medium," said Jim O'Rourke, group media director at Dallas-based Richards Group, an agency that has experimented with TiVo's interactive-ad functions. He says "there is an appeal, even to just being able to time-shift an ad in radio…It gives radio an element that TV could say it has, and print has and the internet has."