He posts longer stuff there than you can with a twitter feed.
Mainly, it seems to consist of random, non-canon, updates, sneak peaks of a single panel of the next strip, postings of panels he didn't use, or protracted commentary on the current arc - for example, we got the more detailed wedding and honey moon.
An example posting, from the wedding, for those who might take interest in such a thing:
"Roast Beef stared into the Eggs Benedict harder than Eggs Benedict have any business being stared into. He had to eat, but tension paralyzed his arms. He wouldn't make it through, or even to, the wedding if he did not eat. He screwed his courage to the sticking point and told himself that if he was strong enough to eat breakfast, he was strong enough to get married. Slowly, he cut away a small wedge of the egg, muffin, ham, and sauce. Ray watched in awe as the bite traveled, on the fork, through the air, slowly, into Roast Beef's mouth. He began to chew. A sensation not unlike morphine began to flow through his veins: nutrition. The fog of his anxiety began to lift."