Users get paid when people shelv their articles and they spread ideas - same incentives as blogging.
Of course we would love to be in retail eventually, and it may be possible. I think the cooler aspect is that you can subscribe to the magazine that PG builds (eventually) or you can build a magazine for your employees to read.
Instead of Chris Anderson choosing what articles are important this month, you can subscribe to Noah Kagan's or a friend from college's magazine.
That being said, I'm not sure how easy it will be to translate blog posts into print in a way that's visually appealing. A lot of bloggers are big into using whitespace, which would look pretty weird in a print medium. And often there is meaning conveyed by the whitespace itself, so it's not necessarily easy to reformat posts into nice paragraphs.
It would be cool if you could get a contract with Starbucks/Borders to put the most popular magazines in the store each month. That way it would give users an incentive to create. Granted, getting distribution like that would be quite difficult.