I have heard from a couple people that it is not allowing them to post. I have noticed myself on occasion that the pencil is not on the blog site for me to write a new post even when I am logged in. If this happens, try this:
1. Go to www.blogger.com and make sure you are signed in.
2. From there you should be able to see a page like this where you can access the pencil:
Let me know if you still are having troubles posting.