As part of the same deploy that introduced plurk, I also snuck in an update to the WordPress service. If you post a url in a message, it will now automatically be converted to a link before being posted to WordPress.
Also, all posts to WordPress are appended with a small “Posted by Composer” link. Eventually premium users will have the option to disable this, but right now that’s not a feature I’ve built! If you’re passionate about this issue, and don’t have the coding skills to remote it on the WordPress end, shoot over a comment and offer me a $50 Amazon gift voucher, then I’ll build it just for you!