And in fact, they are using Twitter to keep up to date on what proxies are working at any given time:

http://search.twitter.com/search?q=functioning+iran

It's going to be interesting to see what happens in these stone age regimes when a communications technology or Internet advancement (this may be quite a bit down the road) emerges that cannot be easily or really blocked at all.

They've learned to block facebook, flicker, friendfeed, and text messaging, haven't they? I'm sure they'll learn to block this too.

But by then hopefully technology and people will have moved onto the next new thing...