There are a number of screenwriters with their own blogs–from small fry like me to huge guns like John August. But there are a number of writers out there who might want to make occasional postings, but don’t really have the inclination to maintain a regular blog.
For writers like that, there’s now a site called The Blank Page, a group blog with posting privileges open to any member of the WGA (the union for film and TV writers). It’s not an official WGA site–WGA membership (or, actually, membership in another country’s equivalent) is just a convenient way of establishing that somebody is a working screenwriter. The Blank Page’s aim is to provide an interesting and low-key window into the life of working writers, so take a look. You might find it interesting.