Problems arose from Sam Sethi's negative (and kind of half-assed, if I may add) comment on the Le Web3 conference, which spurred some insults from the conference organizer Loic Le Meur. Sethi fired back by trying to make Loic look like a jerk in front of everyone, although Loic had apologized, and Mike had specifically asked Sam not to do that. So, Sam gets fired. It's basically your standard editorial stuff, happens every day in journalism. You can read Mike's account of the whole incident here.
This will all be very well covered by, well, everyone, so I hope you'll forgive me if I give a bit of a personal commentary myself.
I'm not saying that Mike was wrong or right, but this type of thing is exactly why blogs should never become big business. When you have one guy behind the computer, working on his blog, then his only concern is quality of content. On the other hand, when you have ten or more websites, dozens of people working for you, conference organizers calling you because they didn't like your post, and, ultimately, hundreds of blogs writing about your decision to fire someone, then you're no longer a blog; you're a business, and we all know that business don't only think about quality of content.
This is not to be taken as an attack on Techcrunch or Mike Arrington; it's just my view on the advantages simple blogs have over traditional journalism. Working professionally in IT journalism for over three years, I very well know that you have to compromise all the time. You're doing a laptop test? If you say (it's just an example) that all Toshiba laptops are crap, Toshiba won't advertise with you any more. It's what happens - it's reality in IT journalism. That's why people write blogs, that's why people READ blogs. Because bloggers can truly write what they really think.
Looking back at Sam Sethi's comment on the Le Web3 conference, from a professional, IT journalist point of view - it's bad. It's short, it's not really objective, it makes things look worse than they are (The wifi for the event did not work and this has annoyed many people - that's your main argument for the whole event being horrible?). But from a blogger's point of view, it's perfectly OK. The guy came to the conference, it was boring, Wi-Fi didn't work, soda was warm, whatever.
So, even if Mike Arrington doesn't consider himself to be a pro journalist, firing Sam was a real pro journalist move he had to make. Welcome to the club.