We just had an earthquake and a quick search of Twitter (about 30 seconds after it happened) showed hundreds of Tweets.  More interestingly it showed that it was felt at least 40 miles west of me which means it was big.

I still don't think Twitter is a reliable news source but this experience was kind of cool.

Addendum: It turns out it was a 5.0 and it was about 30 miles east of me (which in it's own small way proves my point once again in that every tweet I saw was from Los Angeles which made me think the epicenter was west of me).