The comparison is more about subject matter than their spin. Rushkoff always sounds like an economics guy who enjoyed Second Life and Cyberpunk too much. Anderson's ideas are firmly grounded in reality, and don't come off as combative and smug. Just can't dig Rushkoff's substance or style.
I see what you're saying. I think Rushkoff's economics fixation is a fairly recent development. There isn't a whole lot of it in his previous work. I loved "Get Back in the Box," but I recognize that some of Rushkoff's ideas could be perceived as wishful thinking. I think that's his problem with Anderson actually. Rather than reimagining an economics system that isn't built on the idea of artificial scarcity, Anderson is more willing to let the current system change and re-leverage itself to allow big commerce to keep doing what it's been doing since the Renaissance. (I'm paraphrasing what Rushkoff wrote in his critique of Anderson).
I used to think Rushkoff might be a little smug (and based on his track record he probably has reason to be), but the more I read about him and the more I listen to his radio show I realize he's more impressed with what others are doing than with what he's doing himself. He's got a segment on his program called "real people doing real things" that shifts focus away from himself entirely in order to highlight what regular folks are doing across the country in the bottom-up, participatory style of engagement that he's championed for so many years. I highly recommend his show on WFMU. He always has awesome guests, including a few that were also on TSOYA (Steven Johnson).