A couple of people are having problems posting. Probably the most common problem is that you are signed into Google but have not accepted the invitation to be an author on the blog. Or you are signed into Google using a different e-mail address than the one you used to accept the invite. The outcome is the same - you can see the blog, it says you are signed in but you cannot post.
If you need me to send you a new invitation (they do expire after a while) then just let me know.
Otherwise continue the great posts!