Yes, it is possible to use NetNewsWire to post to your blog, but there is a small bug where NetNewsWire is unable to automatically determine your correct "Blog ID" number. This bug is being investigated with the developer of NetNewsWire, and we expect to soon see a version of this software with this bug squashed. In the meantime, you can send us an email and we will provide you with your "Blog ID" number so you can manually enter it. There's a new blogging software for Mac OS X called ecto. ecto is in beta, but it is usable in beta form; it is extremely powerful and is compatible with our system. Choose Movable Type as the API and use the RPC endpoint of http://api.blogharbor.com/xmlrpc.cgi.