Stephen Phelps has written a column about astro-turf here.
Let me chime in here. Aside from taking an amusing swipe at 'the other side,' let me explain why the whole astro-turf issue is a bit more than that. A lot of people have said that all political parties and interest groups regularly issue various "action alerts" including sample letters to send to various people. This is true, but most of the time the "click here to send this form letter under your name" systems are directed not at newspapers for the purposes of publication but for congressional representatives. As such, they are more like signing a petition. I've sent a few of those and I've never expected the recipients to assume it was a letter written in my own words.
In addition, GOPTeamLeader allows the user to send the identical letter simultaneously to up to 5 media sources - which is a bit indecent.
But, really, the main issue about this astroturf was that so many editors published it even though it was so obviously a piece of astro-turf. In fact, one editor communicated to one of my readers that they published it knowing full well that it was astroturf "as a courtesy" to their many GOP readers.