TPI has some good thoughts here on Tea Parties (despite his support of Yglesias, who confounds all by calling tax protestors stupid).
Conversely, Douthat also does a good job of fleshing out thoughts from a less-than-extremist conservative on what the Tea Parties represent.
Personally, I think what liberals like Yglesias are forgetting is that in 2002-2003 when they were all boldly marching against (and chaining themselves to the Bush Ranch in opposition to) the War in Iraq and liberal extremists talked of planted explosives in the Twin Towers and of missiles shooting down planes, the Right collectively called the protesters stupid, and said the conspiracy extremists who were extolling government's hand in the terrorist attacks were undermining the self-confidence of the country and helping the terrorists win. Then, when it became slowly clear that the War in Iraq was...ill advised to say the least...the Left "grassroots organized" and collectively gathered to themselves the ever increasing masses of people who disliked the Republican Party and elected Barack Obama.
So there's this potential parallel going on here. You had 9/11 early in Bush's term when he was uber-popular and then things didn't go well and protesters were all over the place, then he slowly lost the country and became a laughingstock and the lamest duck in 30 years. Now you have Obama as the uber-popular one, preaching and enacting major change (of a different kind than Bush but no less invasive to civil liberty) and protests and rallies are breaking out (three different Tea Parties in Kansas City drew an estimated 10,000 people between them), you have people using stronger anti-leftist rhetoric than ever, and you have Obama's approval rating standing strong...but starting to wane towards the median. Could it be we will all face collosal tax increases in 4-6 years to pay for the uptick in debt from the current Administration's agenda, and the whole thing will blow up into another "I told you so" swing, this time massively to the Right?
I find it highly possible.