My friend Jonathan Wright is the former Cairo bureau chief for Reuters, and now a highly respected literary translator (notably of Khaled Khamissi's Taxi.) He has decades of experience in journalism for an exacting news agency, and has seen real warzones (in fact, he was kidnapped in Lebanon during the 1980s and escaped). I highly recommend that you follow his blog for level-headed analysis and accounts of what has been taking place in Cairo for the last few days, notably his reflections on the media's exaggerated numbers for the January 25 protest in Midan Tahrir:
Media coverage of Egypt's 'Day of Anger' on Tuesday, some of which has been greatly exaggerated, could in fact create perceptions way out of proportion to the events on the streets. Hamdi Kandil, a respected commentator, for example, was just on Al Jazeera saying that 80,000 to 90,000 people took part in the protests. Al Jazeera itself is saying tens of thousands, which itself seems fantastical judging by what was evident on the streets of Cairo (it's hard to judge what happened in Alexandria and Suez). Television footage, by selecting the most dramatic shots and playing them repeatedly, could reinforce the perceptions that there was a true mass uprising. The main effects would be to embolden those who took part, encourage others to join future protests in the belief than there is safety in numbers, and on the other side of the equation throw the government off balance by making it sense a greater threat than initially existed.
P.S. I should add that Twitter is extremely unreliable as a source of info. When I retweet something, it does not mean that I believe it's true — I am just noting that the information is flying around. I feel slightly uncomfortable with that and thus often add TBC (To Be Confimed) to my retweets. And, in my journalism, I would exercise a lot of caution like most in the profession (except the Daily Mail, which put a story on its site alleging that Gamal Mubarak had fled the country with 100 pieces of luggage and has now taken it down rather than issue an apology or correction — what a pathetic attempt at increasing traffic to their site by using a trending story). I also try to be cautious on this blog, a medium that leads one to a certain level of over-enthusiasm. But I always try to correct myself.