I'll suggest an answer to Matt's musings on why we rarely see serious effort funneled into third-party candidacies for House seats, where they'd actually stand a chance. Putting aside the occasional blip -- like Jim Gilchrist in Orange County, or Bernie Sanders in Vermont -- for the folks pushing the third party concept, ideas and even efficacy run far behind aesthetics on their list of concerns. They're in this for the optics of it, and great men don't backbench in the House of Representatives.
Look at it this way: the substantive option is that this group really is concerned about the issues, and believes that, for reasons of political alliances or corporate distortion, the two major parties are unable to reach the right conclusions. But that falls apart under inspection. As others have pointed out, the litany of issues Unity 08 claims to be concerned with sound a lot like the Democratic Party's agenda, yet these folks have detoured off into a quixotic attempt to mount some bipartisan ticket. And they don't actually propose any solutions to their list of concerns -- they're waiting for a charismatic leader to tell them what they think, all they're ready to explain is what they worry about. Indeed, their effort is marked by nothing more substantive than a distaste for substance. Whatever opinions their leaders hold, they will adopt. If you're actually worried about the issues, opening your net wide enough to catch members of both parties and not demanding any particular solutions is an exquisitely inane way to address your concerns.
Which, in the end, means what they're really waiting for is a charismatic leader, one unshackled by the party structure, funding process, or general un-awesomeness of American politics. And since charismatic leaders are useless when they're one out of 435, putting such a person in Congress doesn't make any statement at all. This group wants to look like they've transcended the two-party system, risen above the tawdry muck that's trapped so many others. This is politics as a fashion statement, and a trite one at that. "The Moose" was tilling this soil long before Unity 08. Which makes them, in the final analysis, poseurs. And who wants to join a party filled with those people?