Could Joe Trippi be Simon Rosenberg's Al Gore?
Many people believe Gore's endorsement of Howard Dean was the beginning of the end of the Dean campaign. Not so much because his endorsement was the kiss of death but more because it (1) forced the Anybody-But-Dean forces to close ranks behind John Kerry and (2) the ham-handed way the endorsement was handled irked a lot of people unnecessarily.
Similarly, Trippi's endorsement of Rosenberg could sour a lot of reform Democrats on Rosenberg's candidacy precisely at the moment he most needed to be rising up. Why? Because the endorsement was similarly ham-handed (bad timing, implicit dissing of Dean by Trippi's silence about his former boss, etc.)
Just a quick thought.