And even if it were true, I don't think mob rule is something to be encouraged.
The trending tags on twitter just mean lots of people re-tweeted something. It's the equivalent of emails that say you should forward it to 100 friends to get good luck. In this case it was "You should be outraged by this, re-tweet it!". But the effect is the same.
Or it could just be twitter bots doing the retweeting.
That's a very good comparison in fact.
Live and realtime is instant, as in less than a second or two and at most a minute (in certain contexts).
Friendfeed, for instance, is a live search engine. Update your GChat status or share something on Google Reader. The time to update and be indexed by the main search engine on Friendfeed is seconds.