A new article in Slate says 'probably not':

According to (British sociologist and international joke expert Christie) Davies, among all the factors that led to the Soviet Union’s spectacular collapse, joking didn’t even crack the top 20. At best, he thinks the explosion of Soviet jokes was an indication of a rising political discontent already underway among the populace, not the spark that started the fire. Or as he puts it, “Jokes are a thermometer, not a thermostat.”

Some scholars go further, arguing that not only is comedy incapable of launching revolutions, but it might even have prevented a few from happening. According to this line of thinking, joking among the discontent masses might act as a release, allowing folks to let off steam, instead of rising up in rebellion.

The late great Harold Ramis agreed. Some extracts from a 2006 interview:

Somebody once told me that if you laugh at a George Bush joke, or you send an email cartoon to your friends that makes Bush look like a fool, you feel like you’ve done something significant. “I did my part, I let people know how much I hate George Bush.” But really, what have you actually done? Just expressing contempt for your leaders doesn’t really accomplish anything...

...There were a lot of political films coming out of Europe during the late ’60s. Movies like Costa-Gavras’s Z and stuff like that. I used to go see all of them, and I realized that my righteous indignation was a form of entertainment for me. I loved getting pissed off at injustice. I didn’t do anything about it, I just liked the feeling of being pissed off...

...Usually, satire is intended for the people who agree with you. Did [Michael Moore’s] Fahrenheit 9/11 convert a single person? I doubt it. He’s just a cheerleader for the already liberal crowd.

(BTW, I included the clip above of Bill Murray's speech from Stripes because I read somewhere that although Ramis, who wrote the screenplay, didn't want to make an explicitly anti-Vietnam movie, he did want to sneak in some commentary. Hence Murray's reference to 'ten and one'. )