There is a very nice post here: How to post content to a WordPress blog from the command line
I tried this in Fedora 14 and here is the way to get this working in Fedora
install WordPress::CLI WordPress::Post
Now, once the above completes make sure that the path /usr/local/bin is in you path.
Then you can simply follow the steps in the above blog post and you are good to go. Happy blogging.