Blogilo is an free and open-source desktop-blogging client written with QT4 and available for linux and Windows.

It supports various blogging API's including Blogger, MetaWeblog, MovableType and Wordpress. It sports a full featured WYSIWYG editor and also an HTML editor.

According to its website some of the features are:

• Support for Creating/Modifying/Deleting posts.
• Support for creating drafts and scheduled posts!
• Support for uploading media files to your blog (Just on supported APIs e.g. MetaWeblog and MovableType)
• Support for Fetching your recent blog entries.
• Support for adding Images to post from your system. It will upload them on Submitting post to blog (Just on supported APIs e.g. MetaWeblog and MovableType)
• Support for saving local entries before publishing.
• Saving your writing copy to prevent data loss, at configurable intervals.
• Internal auto spell checker. (KDE spell checker used so most of languages are supported)

Another feature is support for right-to-left languages such as Persian, Arabic and Hebrew.
To install on ubuntu:

sudo aptitude install bilbo

Download Blogilo for other Linux distributions and Windows.