No new releases since March 2012, but last version, 0.7.8, is still working and can be downloaded from the official website.
KeepNote: note-taking and organization. KeepNote is a note taking application that works on Windows, Linux, and MacOS X. With KeepNote, you can store your class notes, TODO lists, research notes, journal entries, paper outlines, etc in a simple notebook hierarchy with rich-text formatting, images, and more. Using full-text search, you can retrieve any note for later reference.