So I went back online and grabbed a screen capture of that Playpen magazine which was seen in the final minutes of last night's premiere of 'In Plain Sight'. And save for a reworking of the cover script, it looks to be the same issue that Charlie found while rooting about in Sawyer's stash on 'Lost' in "Flashes Before Your Eyes":
[Far right and left are from 'Lost'. Center is from 'In Plain Sight'.]
So I'd say we have a definite crossover. My splainin for the difference in the text? Each issue was geared to a different market in the world. The one we saw from 'In Plain Sight' was sold in the Albuquerque area, while Sawyer probably picked his up at the airport in Sydney, Australia.
As for the time difference between episodes? After all, Oceanic 815 took off in September of 2004. For all intents and purposes, the pilot episode of 'In Plain Sight' just happened recently in 2008. Well, my splainin would be that the copy which Marshal Mary Shannon had was also from 2004, and she swiped it from the collection of her semi-boyfriend Raphael.