Both Hackett and Dean were longshots.  That has got to factor into your analysis.  The netroots helped lift both to prominence.  The netroots also helped the Hackett campaign with valuable research, which factored into their press releases and campaign strategy.

If you want success stories of netroots activism, perhaps the best examples are found where the netroots and the grassroots intersect.  For this, I'm thinking specifically of the DFA.  If I'm not mistaken I think their candidates have a 50% success rate, which is none too shabby!  

security.

We lost last cycle in PA 08 but if it wasn't for you guys our campaign wouldn't have had a chance.  You could argue too that we forced the R's to spend over a million slandering Ginny, which kept the fire away from other candidates who won.

We wanted him to be President.  He felt this was the only chance to get America back on track.  So we supported him, backed him and did all we could to help get him there.  

The DLC and other inside the beltwayers that have been trying to pull the party over to the right (basically to try to squash the Democratic Party) joined forces with the Repubs to stop the Howard Dean Presidency.  Their propaganda machine went to work like the Repubs and the majority of the voters bought the electable crap.  All the activists joined forces even knowing it was still a slim chance to get Kerry elected.  But they refused to make the same mistakes again.  The real thing or forget it.

The Hackett campaign clearly showed the lessons learned and the netroots didn't jump ship.  They accomplished a great deal and no matter which way you slice it, the results were amazing.

Howard is correct.  The people have the power.  If you use it, you will win.  Just use it wisely!

Let's look at specific examples:

Where would Howard Dean be without the grass/netroots?

Would DFA exist without the grass/netroots?

How many votes would Steve Young have received without the support of the grass/netroots?

How many votes would Christine Cegalis have received without the support of the grass/netroots?

Some even more speculative questions:

Would the M$M have responded to Cindy Sheehan if the netroots did not exist?

Would there be eight Republicans being indicted if the grass/netroots had not kept the heat turned up on Repubican corruption?

Would Bush have been absolved from blame for the disastrous reaction of FEMA to Katrina without the focus of the grass/netroots?

Personally, I think that the netroots are a fairly limited tool.  In terms of fundraising and rapid response, the netroots are probably the most effective weapon we have.  However, in terms of message discipline, unity, and organizing, there's a long way to go.  It'll be interesting to see how this plays out.  

If you're really interested in this, you should read Ezra Klein's American Prospect article on the netroots impact in the Hackett-Brown primary.  He offers a fairly good analysis of the blogosphere's strengths and shortcomings, and what needs to be done about them.